Design of Wind Turbine Control

Structure of Wind Turbine Control Unique The principle target of this report is the structure and investigation of the control of the breeze turbine. So as to guarantee an effective vitality catch from the breeze and simultaneously the moderation of burdens at regular frequencies, it will be structured the working technique of the machine. Besides, the control of the breeze turbine will be additionally structured so as to guarantee a steady exhibition of the framework given the stochastic idea of the breeze. As a last undertaking, it will be broke down the distinctions and significance of having a framework with a decent or decreased hybrid recurrence. Presentation The misuse of wind vitality is without a doubt the most well known device for the handling of environmental change everywhere throughout the world. The advancement of wind turbines has prompted a variable speed pitch managed design that expects to extricate vitality from the breeze as proficiently as could reasonably be expected. As the infiltration of wind vitality turns out to be increasingly more noteworthy in current force frameworks, there is a need to meet certain rules and nature of age so as to keep up the dependability and security of gracefully over specific levels. So as to accomplish a streamline vitality catch and keep the machine from unreasonable burdens, the structure of both working procedure and controller of the plant should be done. The trouble of the plan depends on the stochastic idea of the breeze, so a cautiously and nitty gritty methodology is required. Additionally, as the controller of the turbine is the core of its activity, the plan of this will turn out to be increasingly more troublesome with the size of the turbine [1]. The bigger the turbine, the more basically adaptable the mechanical parts will become and it is now where the exhaustion loads become a significant worry, as they are firmly identified with the working existence of the machine and furthermore to the operational and upkeep costs. The reason for this report is to feature the significance of the controller and the commitment to the vitality catch, just as the plan of an appropriate working technique that augmented the decrease of burdens while guaranteeing an effective execution. 2.1 Baseline and method The primary goal of the control plan of any wind turbine is to acquire a decent exchange off among vitality and burdens. In factor speed pitch managed turbines it is controlled both pitch and torque. The previous is controlled to confine the streamlined force in above-appraised power (consequently, the heaps), while the last is basically used to control the transmission torque in above evaluated wind speeds and to augment vitality catch underneath the appraised power area. The working procedure must be cautiously plan so as to accomplish most extreme force catch while restricting the streamlined burdens in the mechanical pieces of the breeze turbine, as they are basic parts of the lifetime of the machine. Subsequently, the structure of the working system must incorporate burden decrease as an express target. In this report, the structure of the working methodology has been done with a unique spotlight on the control of the pinnacle and drive train resonances, just as the relief of th e cutting edge loads. So as to structure the working system, it has been given a model of a 1.5 MW variable speed, pitch managed turbine. In the model, it was gotten the mechanical attributes of the machine (Blade length, Gearbox proportion, etc), alongside the force coefficient esteems for underneath evaluated activity, where the pitch of the sharp edges was - 2 degrees and is fixed for beneath appraised activity. With the above information, it was conceivable to set the Cp-Þâ » bend of the machine. This kind of bends are utilized in wind turbine configuration to acquire rotor power for any mix of rotor and wind speed. By building this bend it is conceivable to get the most extreme force catch. This is given by the force coefficient Cp, that it is a connection between the force in the breeze stream and the force created by the turbine [2]. The ideal working system must attempt to accomplish the most extreme force catch, and consequently the greatest estimation of Cp, and such working point decides th e ideal tip speed proportion (Þâ »), which is the proportion between the rotor speed and the breeze speed. When the ideal purpose of intensity extraction is set, it is conceivable to assemble the model of the machine. For this machine, the generator will work in a range between 1 rad/s and 170 rad/s. In this manner, having the gearbox proportion, it is conceivable to acquire the rotor speed given the accompanying condition: By acquiring the scope of rotor paces of the machine, it would now be able to be determined the essential breeze speed for every rotor speed with the accompanying condition: Where Þâ » speaks to the ideal tip speed proportion of the machine, which compares to an estimation of 8.4 in this plan (for a Cpmax of 0.47). This scope of wind speeds is utilized to acquire the streamlined torque, which is an element of the rotor speed and wind speed (when the pitch edge is fixed). Along these lines, it is conceivable to infer the air torque by the accompanying condition: Where the estimations of and relate to the ideal working point. That is, for a given breeze speed and rotor speed, the goal is to create a torque with the end goal that the force extraction from the breeze is greatest. Accordingly, the above condition will give the torque esteems to the most extreme vitality following district. Then again, it is important to get the generator torque, as this will be utilized so as to decide the finish of the first and second steady speed (To and T1). As it tends to be found in the condition beneath, the damping misfortunes have been thought of. For this structure, a damping of 5 has been accepted. The generator toque can be gotten by the accompanying condition. Presently it is conceivable to get the force created in the machine by having a proficiency of 95% in this machine: Also, the torque at evaluated intensity of the machine is given by: Where the evaluated power bend crosses with the subsequent steady speed line, will decide the torque which will produce at above appraised activity. At long last, it has been determined the qualities for the steady speed bends of the working methodology. It has been applied condition 2.3, setting the breeze speed steady (from 4 m/s to 12m/s) and determined the torque for the various estimations of Cp and Þâ ». The subsequent working procedure will be with the end goal that will cross each steady wind speed by where is the ideal force extraction point (Cpmax). 2.2 Operating procedure process A few components must be considered in a working technique structure. Having gotten the qualities in the past segment, it is conceivable to plot the most extreme force extraction bend. The plan must have unique spotlight on the normal frequencies of the pinnacle and cutting edges. For this structure, it has been given the common frequencies of the two segments. For the pinnacle, the side-side and front toward the back frequencies. For the sharp edges, the edge and fold frequencies were given. In light of this, it must be investigated and contrast those frequencies and the rotor speed (P), the 3P and the 6P part. It is alluring to plan a working system that abstains from working at products of the basic frequencies, as they are basic purposes of activity where the mechanical burdens increment and the lifetime of the turbine can be decreased because of weakness loads. Also, the methodology must guarantee a smooth exchanging at the first and second steady speeds with the working bend. This has been accomplished by setting both steady speed lines with a base length, in such way that the controller of the turbine is exchanging the to various activity modes exorbitantly, as this could diminish the productivity of the machine. Another significant viewpoint to see when planning the working system, is to guarantee that the breeze turbine activity isn't near the slow down front. The slow down front bend is the bend that associates the most extreme purpose of the consistent breeze speed bends. It decides the start of the slow down locale where the sharp edges will be presented to high loads and the force extraction won't work effectively. In light of the abovementioned, the plan of the working technique was completed. The primary steady wind speed was set at 1.2 rad/s, maintaining a strategic distance from a 6P recurrence in the sharp edges (fold regular recurrence) that would show up at roughly 1 rad/s. As the plan of the working methodology must be an exchange off between vitality catch and decrease of burdens, it was chosen the above as the most ideal alternative for this machine. Rotor speed (rad/s) Generator torque (Nm) Streamlined Torque (Nm) Clench hand steady speed district (end) T0 1.2 1432.923 163076 Second steady speed district (starting) T1 2.02 4640.24 462004 Appraised torque 2.02 10137 853106 Table 2.0 generator torque at steady speed exchanging point The start of the subsequent steady speed district is controlled by the most extreme generator speed which has been set at 170 rad/s (2.02 rad/s at the rotor side). It very well may be found in Figure 2.0 the working technique bend of the machine, where it tends to be evaluated that the working system has maintained a strategic distance from the 6P regular recurrence expressed previously. The slow down area is far enough from the working locale of the machine, guaranteeing a decent exhibition and better productivity. Figure 2.0 Aerodynamic torque-rotor speed graph. Working technique bend of the breeze turbine 2.3 Discussion of results By and large terms, the plan of the machine has been effectively done, as it tends to be found in Figure 2.0, covering the accompanying basic parts of any working methodology of a breeze turbine: After deliberately broke down the regular frequencies and contrasted and the 3P and 6P reverberation frequencies, it has been set the cut-in speed of the machine at 1.2 rad/s. Additionally, this technique will guarantee that the damping misfortunes in the machine don't have unreasonable impact on the influence produced, as at extremely low rotor sp

Wave-current interaction Essay Example | Topics and Well Written Essays - 750 words

Wave-current connection - Essay Example These amazing and shifted powers can unleash significant harm on a wide assortment of human movement, making â€Å"reliable expectation of wave movement in beach front regions †¦ pivotal to seaside building applications related with nearshore morphologic change and harbor/gulf support †¦ In certain territories, be that as it may, encompassing flowing and different flows can be solid and their impact on wave change can be generous. They make a Doppler move and cause wave refraction, reflection and breaking, which can bring about by and large redistribution of wave energy† (Chen, Panchang and Demirbilek, 2005). A comprehension of a few key terms is important to the conversation. The term wave-momentum collaboration is utilized to depict the different manners by which wave tallness, frequency and wave vitality are influenced when a wave experiences an ebb and flow (French Research Institute for Exploitation of the Sea, 1998). â€Å"Wave tallness is the good ways from a waves trough to its peak †¦ The peak is the highest point of a whole wave, the trough is at the base of the front of the wave† (Wave Basics, 2006). Frequency is commonly acknowledged to mean â€Å"the separation in an occasional wave between two purposes of relating stage in back to back cycles† (Stewart, 2005) or an estimation of â€Å"the length between the top purpose of one wave, and the highest point of the next† (Explaining Waves, 2005). Wave vitality can be clarified as a concentrated type of sun powered vitality as swells are made by the cooperation of wind on the water surface, moving sunligh t based vitality to the water (Ocean Wave Energy, 2005). Expectation of these wave movements are made entangled with the presentation of refraction, reflection and breaking. Refraction is â€Å"a process in which the wave peaks will in general equal the profundity contours† (Coastal Change, 2003) after entering shallow waters. â€Å"The impression of

Organizations Diversity Policy and Practices Report Analyses

Question: Portray about the Organizations Diversity Policy and Practices for Report Analyses. Answer: Official Summary The report investigations authoritative assorted variety in a social insurance unit of United States. The picked association is New York-Presbyterian Hospital. The medical clinic is not-for-profit instructing association. The report examinations multiculturalism and decent variety in the association. Because of an inundation of settlers and increment in populaces, social decent variety in the association is watched. The examination considers the job of nursing work power in the human services unit. Effect of differing workforce on patients results Because of inundation of migrant in nation, the New York-Presbyterian Hospital encounters social assorted variety among the nursing staffs. Heterogeneous patient base in the social insurance association is important to serve the patients in a productive way. The nursing staffs require carrying on reasonably to serve understanding with various qualities and alternate points of view. Pilips Malone (2014) referenced that a very much expanded work culture upgrades profitability in the social insurance unit. The degree of value administration gave to the patient abatements if social separation and provocations are available in medicinal services unit. In US, it is seen that the normal time of medical attendants has expanded from 39-43 years during most recent 10 years. In addition, the level of minority and ladies populace has expanded in work power. Number of youthful alumni is likewise expanding in nursing calling. Subsequently, decent variety is expanding both as far as culture and dialects. Racial segregation in America is still presents. Assorted variety in workforce lessens the separation in understanding consideration. According to report of US Agency of Healthcare and Research quality, the white patients get greater quality human services contrasted with minority and dark individuals (csahq.org, 2016). Effect of multiculturalism and assorted variety on human services Pilips Malone (2014) referenced that enrollment of minority nurture in the authority position can take out the social segregation and medicinal services incongruities in the human services unit. Aside from the racial separation, there are different sorts of social assorted varieties, for example, language, religion, sexual orientation, age and incapacities, financial status and so on. A decent act of culture requires being adaptable with other independent of various culture. In the event that the medical attendants can embrace the social want, they can have the option to give equivalent consideration to all the patients. Acknowledgment of social decent variety is required for different representatives of the human services unit to build the adequacy of the medicinal services administration of the foundation. Current enrollment and maintenance arrangements of New York-Presbyterian Hospital to discover holes between best practices and current strategies New York-Presbyterian Hospital assumes significant job in keeping up social assorted variety in the division of medication and essential medicinal services unit. This association offers significance to the enlistment of minority staff in both the patient consideration unit and research zone. The people group administration plan 2013 delivered by New York-Presbyterian Hospital features that the administration sorts out an improvement program to address wellbeing needs of minority and outsider networks by joint effort with nearby wellbeing specialist co-ops (nyp.org, 2013). As per the perspective on Douglas et al., (2014), the patients who experience the ill effects of ceaseless illnesses, destitution, and separation issue, face issues to get to social insurance because of social distinction. In this manner, it is significant for the social insurance units to address the issues for the improvement of human services framework. Usage of the strategy taken by the New York-Presbyterian Hos pital might be fruitful to expel variations in the social insurance benefits in the area. Appraisal of level of incorporation in the New York-Presbyterian Hospital and significance of multiculturalism During 2011, the New York-Presbyterian Hospital sorted out a territorial wellbeing community program to offer equivalent quality support to the patients having a place from various societies. They built up a populace based social insurance model to improve social assorted variety and information among the medicinal services specialist organization of the association (Carrillo et al., 2011). This model was created to diminish wellbeing incongruities at singular level just as populace level. Execution of the patient consideration model helped the association to give broad medicinal services administration to an enormous number of low salary gathering and Spanish-talking individuals in the locale. Proposals on proof based changes in framework Collective authority approach is compelling for the social insurance association, where the representatives need to cooperate to deliver common advantage in human services administration. Collective correspondence among the partners, information sharing, decrease in intricacy of authoritative structure can viably expand the nature of social insurance administrations (Al-Sawai, 2013). In training medical clinic like New York-Presbyterian Hospital, individuals have distinctive degree of obligations. Coordinated effort among a few divisions and workers expands the comprehension of various social practices in the association. The individual exertion of nursing administration and supervisor can spur the medicinal services specialist co-op to act reasonably with patients independent of various social foundation. References Al-Sawai, A. (2013). Authority of Healthcare Professionals: Where Do We Stand?. Oman Medical Journal, 28(4), 285-287. Recovered from https://dx.doi.org/10.5001/omj.2013.79 Carrillo, J., Shekhani, N., Deland, E., Fleck, E., Mucaria, J., Guimento, R. et al. (2011). A Regional Health Collaborative Formed By NewYork-Presbyterian Aims To Improve The Health Of A Largely Hispanic Community. Wellbeing Affairs, 30(10), 1955-1964. Recovered from https://dx.doi.org/10.1377/hlthaff.2011.0635 Douglas, M. K., Rosenkoetter, M., Pacquiao, D. F., Callister, L. C., Hattar-Pollara, M., Lauderdale, J., Purnell, L. (2014). Rules for actualizing socially skilled nursing care. Diary of Transcultural Nursing, 25(2), 109121. nyp.org (2013). network administration plan 2013 Retrieved 2 August 2016, from https://www.nyp.org/pdf/communityserviceplan2013.pdf Pilips, J. M., Malone, B. (2014). Expanding racial/ethnic assorted variety in nursing to decrease wellbeing incongruities and accomplish wellbeing value. Nursing in 3D: Diversity, incongruities, and social determinants, 129(Supplement 2), 4550. Recovered fromhttps://www.publichealthreports.org/issueopen.cfm?articleID=3081 Why assorted variety matters in Health Care (2016). Recovered 2 August 2016, from https://www.csahq.org/pdf/notice/issue_12/Diversity.pdf

10 Best Clubs To Join In College By

Clubs add splashes of colors on your stay in campus. It can become a great source of support, especially during the rough weeks, or simply an outlet to combat stress. Whatever the case, joining a club while in college is definitely one of the key points of the taste of life away from home. The question is what are the best clubs to join in college? There is only one answer for that, the one where you know you will enjoy the most. Here are some of the best choices in choosing the best club to join in college.1. Build Your Own Club!We are not kidding. If you have a certain interest which you cannot find in any club available at your university, you can actually form a club of your own as long as it adheres to the policies of your school regarding club activities. Founding a club can also be a way of impressing your future employers, but ensure that you are willing to allot precious time on this club for it to flourish. Creating a club, or joining a club per se, requires as much passion as choosing a major in college because you are going to be with it for as long as you are studying.2. Food or Cooking ClubNo matter what course you are taking, a food or a cooking club will always be one of the best choice, because hello? Free food! Apart from the freebies, you can also utilize everything you will learn from this club for your own good for instance, it can give you ideas on quick and easy recipes for your wee-hours-of-the-night cravings, as well as allow you to learn the simple dorm meal recipes so you can finally start on that healthy lifestyle. Above all, if you are a culinary arts major, what best option could there be other than this club! (But, seriously though, this is really the best club you can join in college especially if it is your first time to be away from home and living the dorm life.3. Helping Hand for Animals ClubThere is probably one club named like this somewhere out there, but that is not specifically what we mean here. Regardless of who you a re or where you come from, you will definitely need a quiet time at least once every two weeks to maintain your peace of mind amid all your academic papers and it does not have to be really quiet. It can be perfect especially when you use your free time in aiding a few of our furry friends out there who are in need of love. If you are an animal lover, this club is perfect for you and the level of happiness one can get from simply helping out can never be matched. Who knows? Spending some time with these animals in need can give you an idea on your future research papers or dissertation, or maybe give you an idea on how to write your law essay.4. Sorority/FraternityIt may be a little difficult for some to make new friends in college, and there will come a time that one will just think of letting it be, however, note that a friend is an important college must-have and a sorority or a fraternity is the best way to meet people who share common interests with you. The idea of joining a sorority or fraternity group carries a number of misconceptions, sometimes weighed more than its official purpose to promote camaraderie among a sisterhood or brotherhood without judgment. It is not just to make you look cool, it is a chance to know yourself better. Furthermore, such organizations will give you a number of opportunities to meet new people and form connections which can ignite an exchange of ideas to help you widen your ideas. Sororities or fraternities are usually designed to offer community service.5. Religion-Related ClubThe contemporary society is peppered with a lot of rights and it is your right to practice your own belief as long as you do not step on the rights of other people, and a university-based club related to your religious beliefs exercises that freedom well.6. Performing (Cultural) ClubAn acting club is not always available in the university scene, and if it is indeed unavailable in where you are, refer to item one. Passion starts to grow in middle school, and we all develop hobbies and talents in those crucial years including performing. Remember that you cannot let that passionate part of you to wither away just to look cool because the reality is we all need the art to survive. Being a college student does not mean you need to forget all about singing, dancing, or acting - it is just a matter of time management. Lets face it... Books and knowledge feed the mind, but arts and beauty feed the heart.7. Photography ClubIf you love art but are not the performing type, surely, you are the one who moves within the silent realm of beauty with a camera on your hand. At some point, you will find yourself at loss with all the academic assignments you need to deal with and stress can only make your desk messier, and believe it or not, forcing yourself to deal with it is just another waste of time. You need to stand up and walk away from your study desk for a few hours and do something else - grab that camera that has been missing you f or quite some time, and walk around outside. Your talent will come back and snapping away the scenes you see outside will rest your mind. Of course, make this experience better with other people who shares the same hobby. Maybe learn to operate a vintage SLR, develop your own stills in a red room, and talk to people. Know that your mind can be exhausted even though the body is well-rested.8. Gamers ClubYour video games might be the main cause of why you end up having a date with Mr. Procrastination, so might as well use that hobby of yours to form real-life friends and connection. Furthermore, finding a club that focuses on the gaming activity will straighten out your schedule. This type of club will give you a set time for gaming, so you can use the rest of the day meeting your schools requirements. The other members could also become your study group. Aside from playing games being a simple hobby, it can also help you how to generate income from likes and in terms of views, shares , and likes simply by video streaming your online.9. Entrepreneurship ClubFor all the sales or business major students out there who wish to hone their skills in the field, an entrepreneurship club will work wonders for you. Primarily, this club will allow you to practice the industry you are aiming for, and that includes the benefit of seeing practical errors and correcting them first-hand - an advantage you can have up your sleeve when you finally pave your way into the business world. The mere joining of this kind of club will also improve your public speaking and persuasion skills, because, well... Sales! You will be able to develop a product, craft a marketing research for it, concoct an advertising plan, and actually make a few bucks. Now, if you are indeed passionate about this course, you will certainly have the time of your life as you continue to learn.10. The School PaperMore often than not, every university has its own student paper, and there are a number of writers in every classroom. If you are well-aware of your talents in writing, then it would not hurt you to try to join the campus newspaper team. It does not have to writing about current events in the university, it can be about anything. Awaken your writing spirit, and grab the opportunity toimprove your writing skills within the same location you are taking your academic course.Hear some thoughts of various students about being engaged with various extra-curricular activities like joining fraternities or sororities:Essay writing service for studentsAs you ponder on your club choices, you should remember that joining clubs entail heavier workloads. You may find yourself struggling to find time for other activities, and where do you squeeze in those essays due days from now? is an academic writing service, dedicated to helping students like you. Our services encompass many writing projects, from the simplest of things like your custom essay, down to the more complex ones like your custom re search papers and custom dissertations.

Essay On How To Build The Future - 906 Words

Welcome to How to Build the Future. Today, our guest is Mark Zuckerberg. Mark, you have built one of the most influential companies in the history of the world. So we are especially excited that you’re here. I’m not sure where to go from there. Why don’t we start with just the early days of Facebook? Tell us what it was like when you started it. Sure. So for me, the thing that I was really fascinated by and always have been is people and how people work. You know, when I was in college, I studied psychology and computer science. And you know, one of the things that you learn when you study psychology is that there are all these parts of the brain which are geared just towards understanding people. Understanding language, how to†¦show more content†¦There’s nothing that was like super interesting there. But that just struck me as you know, people have this deep thirst to understand what is going on with those around them. And you know, there were probably, you know, 10 other things like that I built when I was at Harvard before I actually got around to building the first version of Facebook. That kind of added a lot of these things together. So as you look back, is there something that made Facebook different from the other projects that you have built that allowed it to turn into this, the company it is today? Well, for one, I think we kept going, right? So I mean, the others, I mean â€Å"Course Match† and you know, just the other different crowdsource tools you know, they kind of served their purpose and then we were done. Whereas with Facebook, there’s just such†¦You know, people loved it and had such an intensity of using it. I think within a couple of weeks, two-thirds of the students at Harvard were using it. And all these other students at MIT and other local universities were writing in, asking us if we could open up Facebook at their school, so we kind of just followed that. 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The Legislative Branch free essay sample

The Legislative Process A. The first step in the legislative process is the introduction of a bill to Congress. B. A bill must pass through both houses of Congress before it goes to the President for consideration. III. Powers Of Congress A. All legislative powers in the government are controlled by Congress; making new laws or changing existing laws. B. The powers of Congress fall into three categories: special, implied, and expressed. Our Government: The Legislative Branch What is the Legislative Branch? Article I of the Constitution talks about the Legislative Branch. The Legislative Branch is the branch of the federal and state governments empowered to make the laws that are the enforced by the executive branch and interpreted by the judicial branch. The Legislative Branch consists of the House of Representatives and the Senate which forms U. S. Congress. If a states population increases, that means the number of representatives increases also. We will write a custom essay sample on The Legislative Branch or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page There were 59 members at the first session of the House of Representatives. Today the House of Representatives consists of 435 members divided among the 50 states. Members of this house are elected every two years and must be at least 25 years of age. Also they must be a U. S citizen for at least seven years. The House has quite a few powers such as initiating revenue bills, and electing the President in an electoral tie. Now the Senate consists of 100 senators, 2 for every state. To become a senator, you must be at least 30 years old, a U. S citizen for at least nine years, and resides in the state that you represent. Senators are elected to six year terms by the people. Only the Senate can approve or reject treaties and presidential nominations for government offices. Senators terms are spread over a period of time so about one third of the Senate is up for reelection every two years. The vice president may cast the decisive vote in an event of a tie in the Senate because he serves as President of the Senate. In order to pass a law and send it to the President for his signature, the House of Representatives and the Senate must both agree on the law. If the President vetoes a law, they may overrule his veto by passing that law again in each chamber with at least two thirds of each body voting in favor. The Legislative Process The Legislative Process officially begins with a proposal in one of four forms: Bill, Joint Resolution, Concurrent Resolutions, and Simple Resolutions. But bills are the most common so I’m going to talk about the bill. The first step in the legislative process is the introduction of a bill. Members of the House of Representatives and the Senate both come up with a bill for consideration by the Congress. The President, head of a Federal agency, or a member of a cabinet can also propose legislation. When a bill is introduced, the title of the bill goes in the House Journal and printed into the Congressional Record. The clerk assigns the bill a legislative number and the Speaker of the House assigns the bill to the appropriate committee. Next, the bill is debated on the floor and then sent to the committee. Once the bill is revised, it is brought before the House of Representatives and Senate for consent again. The bill may be referred to a conference committee committee composed of both the House and Senate to settle differences in similar bills. Committee rejects the bills by not acting on them. The bill is then brought before both the House of Representatives and Senate for approval. Members of them both vote on the final version of the bill. If the bill is approved by the House and Senate, it is sent to the President. When the President receives the bill, he may sign, veto, or pocket veto the bill. If he signs it, the bill becomes a law. If he vetoes it, it goes back to Congress for redrafting or Congress can override the veto with two-thirds majority vote in both chambers. If the President does not return the bill to Congress with his disagreements within 10 days or so, the bill can automatically become a law. If Congress adjourns before the 10 day period, the bill is vetoed. And if Congress wants to pass this legislation, they must begin an entire new process. Once the bill is signed by the President, the laws are given public law numbers and copied in printed form as slip laws. These Public Laws are then bound into the Statues of Large. In each two-year session, thousands of bills come before Congress. Almost twelve thousand bills were introduced in Congress in one recent session. Less than five hundred were enacted into law. Powers of Congress Congress is the only part in the government that can make new laws or change existing ones. The President may veto bills Congress passes, but Congress may override a veto by two-thirds a vote in both the Senate and the House of Representatives. Congress is also empowered to pass laws deemed â€Å"necessary and proper† for the carrying out of powers given to any part of the government. Powers granted to Congress fall into three categories: implied, expressed, and special. Implied Powers are powers not listed in the Constitution. They come from and depend on expressed powers of the government. The basis for implied powers comes from the necessary and proper clause of the Constitution, Article 1, Section 8. Another name for implied powers is called the elastic clause because it stretches the power of the government. Implied powers have helped the government enhance its authority to meet the many problems and situations that the Framers unseen. Expressed Powers are those powers explicitly named in the Constitution. They grant the legislative branch a large amount of authority over American national policy, both domestic and foreign. The Constitution states that the Congress shall have power to lay and collect taxes, imposts, duties, excises, to pay the debts and provide for the common defense and general welfare of the United States; but all imposts, duties, and excises shall be uniformed throughout the United States (Brady). There are a total of 27 expressed powers listed in the Constitution. Congress retains a number of special powers. It can act as a judicial body to impeach and try a president or other civil officer for misconduct. For example, the House of Representatives impeaches the official and Senate does a trial. Congress is also empowered to create and use administrative agencies and boards, such as the National Highway Traffic Safety Administration, to determine facts and to enforce its legislative policies and enactments. Other than that, the Constitution vests each house of Congress with different powers as well.   References: Collins, Philip R. Power of Congressional Committees of Investigation to Obtain Information from the Executive Branch: The Argument for the Legislative Branch. Geo. lj 39 (1950): 563. Edin, Per-Anders, and Henry Ohlsson. Political determinants of budget deficits: Coalition effects versus minority effects. European Economic Review 35.8 (1991): 1597-1603. Evans, C. Lawrence. Politics of Congressional Reform. The Legislative Branch (2005): 490-524. Cohen, Julius. Judicial Legisputation and the Dimensions of Legislative Meaning. Ind. LJ 36 (1960): 414. De Haan, Jakob, Jan-Egbert Sturm, and Geert Beekhuis. The weak government thesis: Some new evidence. Public Choice 101.3 (1999): 163-176. Schickler, Eric. Institutional Development of Congress. The Legislative Branch (2005): 35-62.

Its effect maranao culture free essay sample

In our paper which is â€Å"Modern Life: Its Effect in Maranao Culture’’ the member of this group are all Maranaos which is we can all relate to the topic, it has many changes nowadays in our generation, the Maranao was slightly lost because of new technology and by the affection of some adapting other culture. As a one of Maranao youth, we are the one who let our tradition to forget our tradition of cultures. In this case, people who belong to this culture must know what she/he should do. Which we can found out about traditions, fashion and styles, food etc. and look back from past to present, we can realize that some of this were already forgotten and hidden through the effects of the modern life which Maranao’s are adopting the other tradition and culture. We as youth of this culture, we are focusing to our culture to highlight this case for us to be aware of this changing environment of the people. We will write a custom essay sample on Its effect maranao culture or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page In addition, we would like to measure how the culture is far from primitive life of Maranao and encourage ourselves to be aware to this problem. Is this modern life affecting the image of MARANAO CULTURE? Are maranao youth is concern to this situation? Otherwise, how can we handle and improve this case. II. KNOWLEDGE ABOUT MARANAO CULTURE A. According to Education The past culture of the maranao is uneducated they don’t know how to write and how to read in this since that they believed that education is not important in their lives, they don’t care about education the most important of them is money, and also they are very strict in terms of money. Most of their parents do not agree in education and they cannot send their children in school because most of them believe that even though you are professional you cannot earn money, and they are jobless. Not like now the most the maranao really want their children to finish the college degree, and even though there is no wealth to leave for them. The important is the education for them, there is a time that wealth can let from you and remember that your knowledge or education is always there to help you to become a better person. As a Muslim, we all know that our parents are not always there hoping for this money or wealth, we cannot stand for our foot. So let us stand by our own feet by educating ourselves. B. According to Fashion style Malong- a malong bearing â€Å"okir† designs. Meanwhile, the malong is a traditional â€Å"tube skirt† made of hard woven or machine-made multi-colored cotton cloth, bearing a variety of geometric or okir design. The malong is akin to the sarong worn by people in Malaysia, Brunei, and Indonesia. The malong is traditionally used as a garment by numerous tribes in the southern Philippines and sulu archipelago. Usually, hand woven malongs made by Maranaos, Maguindanao, and t’boli Weavers on a back strap loom. The pattern or style of the malong may indicate the weaver’s tribal origin, such as the Maranao malong landap. Very rare malong design and styles can indicate the village in which the malong was made, for example, the extremely intricate malong rawatan made only by handful or maranao weavers in Lanao del sur, Mindanao. Hand woven malongs, which are costly malong, are likely to be used only at social function to display the social and economic status of the wearer. While modern malongs are made of cotton and lurex threads. Some contemporary hand woven malongs are made of expensive rayon thread, to reduce the manufacturing cost to the weaver and ultimate cost to the consumer. There are many gardens of cotton thread, and cost of the malong can also be every by using the uses grades of cotton thread, or by creating a loose coarse weave. Machine-made printed cotton malongs are made in Indonesia specifically for export to the Philippines and are commonly referred to as â€Å"Batik† because the item is imported those in expensive machine made malongs are used for very purpose. The malongs can function as a skirt for both men and women, a dress, blanket, a sunshade, a bed sheet, a dressing room, a hammock, a prayer mat and other purpose it new born is wrapped in a malong, and as grows this piece of cloth become a part of his daily life. When he is dies, he is once again wrapped in a malong. Among traditional tribal peoples, the malong is used in everyday life. Even if an areas where people wear western style clothing during the day, the malong commonly used as sleepwear. The malong is also use in very big festivals; they wear this to show respect. C. According to Rites / Rituals Kinship System. There are special practices in the address system when one deals with the royalty and nobility (i. e. the datu and salip). One never or seldom refers to a datu as Datu X. The normal practice is to use teknonymy, i. e. by reference to his first child. Thus, Datu X should be called Bapaq ni Y. Among the nobility, bapaq is preferred to the more common ama. Courtship and Marriage. Marriage in Maranaw society is not just a simple romantic one-to-one relationship between boy and girl; rather, it is a fusion by affinal ties of two families seeking to establish socioeconomic and political relations with one another. Traditional marriage has therefore always been contracted through parents, although the practice is slowly becoming modified to conform with the times. It is, therefore, clear why the reckoning of the salsila, genealogical record, occupies a significant niche in the Maranaw mind. In fact, in considering marriage, what the pananalsila salsila expert says or reveals about the lineage of the parties concerned can become crucial in the decision to proceed with the marriage or not. It is part of ones group consciousness or pride (maratabat) to see the individuals marriage establishes strong family relations. The fact that the Maranao marriage involves more than just two individuals makes it a big social event from the start. The exchanges of poetic ballads (bayok) and courtship language (kadadaonga) between the parties involved, through go-betweens and spokesmen, become a form of nightly entertainment for the entire village. People congregate and socialize on these occasions. It may not even be too far-fetched to assume that gatherings like this contribute to the development of social cohesiveness within the village or between the two villages to which the two families belong. If the negotiations on the bride-price (sunggod) goes smoothly, the parties determine the wedding date and the various details of the wedding celebration. As the wedding day (kambitiara) draws near, arches are built and buntings of various sizes and shapes are hung. For at least a week before the kambitiara, kulintang music accompanied bossed gongs and drums create an atmosphere of festivities. Sports, like the kasipa sa manggis (a game of skill, the aim of which is to drop a suspended cube by kicking a rattan ball) is indulged in. And finally, on the wedding day itself, the groom arrives in a very colorful procession, attired in the most expensive wedding costume the family can afford. The wedding rite (kakawing) itself is simple. The imam holds his thumb up with the thumb of the groom and covers them with a white handkerchief. He recites a prayer from a Holy Quran, gives advice to the groom, and asks the consent of the womans parents. This done, he searches for the bride who has been hidden all this time somewhere in the house. When he finds her, he touches or kisses her forehead, marking the beginning of the couples marital life. D. According to Tradition Maranao is the term used for the people of lanao, a predominantly Muslim region in the Philippines islands of Mindanao. They are famous for their artworks, sophisticated weaving, wood, and metal craft, and their epic literature. The word Maranao, also spelled Maranaw, means â€Å"people of the lake† referring to the indigenous people who inhabited the lands around lake lanao whose principal town is Marawi city. The Maranaos are part of the wider moro ethnic group, whose constitute the sixth largest Filipino ethnic group. The life of the Maranao is centered on Lake Lanao, the largest in Mindanao, and the second largest and deepest lake in the Philippines. This breathtaking beautiful lake surrounded with myths and legends, it is the main source of fisheries, and the main source of hydroelectric plant installed on it, and the Agus River that generates 70% of the electricity used by the people of Mindanao. A-commanding view of the lake is offered by Marawi city, the provincial capital. a. Language Maranaos is an Austronesian language spoken by the maranao people in the province of Lanao Del Norte and Lanao Del Sur in the Philippines. The language of these people is called Maranaw or Maranao. The difference is only a matter of spelling. The term Iranon, if used, refers to a speech variant of Maranaw. In 1948, the Census stated that there were 135,241 who were able to speak Maranaw. In 1960, the number of mother-tongue speakers was 150,674. In 1970, this figure increased to 541,838. b. Art and Musical heritage Maranaw art is very distinctive. Mats and cloth from Lanao are decked in flamboyant colors. Intricate traditional designs grace the peoples gleaming brassware and handicraft. The Maranaws weave not only cloth and mats but also bags, centerpieces, placemats, and unique neckties. Sarimanok is a legendary bird of the Maranao that has become a ubiquitous symbol of their art. It is depected as a fowl with colourful wings and fethered tail, holding a fish on its beak or talons. The head is profusely decorated with scroll, leaf, and spiral motifs. It is said to be a symbol of good fortune. The native Maranao have a fascinating culture that revolves around kulintang music, a specific type of going music, found among both muslim and non- muslim group of southern Philippines. Biyola is another instrument for the Maranao people to use Biyola is a string instrument. Music is another important part of the culture. However, it should be noted that there is a distinction between music for rituals, which is basically vocal without instruments, and music for entertainment. Kulintang (brass gongs), kagandang (war drums), ceremonial dances and kambaioka (singers or chanters of improvised poetic compositions) are played on various occasions. The gabbang is similar to a xylophone, whilesuling and saunay are wind instruments. The biyula is a string instrument, and the kulintangan is an ensemble of gongs and drums. The kudyapi is a two-stringed lute plucked to make beautiful sounds. The kubing (jew’s harp) is made of bamboo and believed to make words and tell stories, if the audience could understand the language of music. Moro musicality is also seen in songs and dances. For the Tausug, there are songs called kissa , which tell about the love of datus and princesses, while heroic songs are contained in parang sibil. The Maranao kandidiagaois a melodious lament over the dead. There are five major types of songs for the Maranao. The kambaiok is the free rhythmic rendering of the baiok, which is improvised poetry. Kandarangen is accompanied by a gong or other similar instruments. Kadikir is sung by singers in slow, free rhythm and speaks of verses from the Qur’an and Maranao compositions with topics on Islam, morals, life, and death. Kandomana is a combination of styles of Kandarangen and Kadikir. Lastly, kapranon is a song of private sentimentality sung softly. c. Cuisine Exquisite Maranao cuisine and hospitality are palpable. They are known of having a spicy taste in their foods. A condenment made of traditionally cultivated spices, locally known, as Palapa is one of their distinguished cuisine symbols. It is made of stewed scallion bulbs or â€Å"Sakurab’’ in Maranao. They thinly sliced scallion bulbs and ginger are caramelized by slow cooking and mixed with chilies little coconut oil. Paganamaranao is their native way to welcome special guests and visitors. This is a customary and traditional conduct depicting their innate hospitality, carried out in and ilegant festivity and gaitey in a manner acceptable to Islamic laws and principles. Generally, during paganamaranao, both the hosts and the guests are expectedly well dressed in maranao or tutubs, the maranao’s native dress. Maranao recipes are so rich that it talks about life itself. Suffice it to say that the recipes are intertwined with the life cycle rites and rituals of all aspects of maranao society and culture: from birth to death. In other words, food cannot be separated with daily life activities because food is life itself. III. CAUSES AND EFFECTS IN MARANAO CULTURE A. Causes of Maranao culture Maranao teenagers are easily attracted to modern lifestyle. There are lot of thing that get their attraction and they can’t stop their temptation. They are also being influenced by the new technology. Having lack of information and interest to the culture. B. Effect in Maranao culture Many things had change in Maranao culture. They way how Maranao dress up, the way they talk, and also the way they act. As times pass by, Maranao people forget their culture and practices. Nowadays, a Maranao teenager keeps imitating modern lifestyle. You can barely see Maranao teenagers girls wearing a â€Å"Kumbong or Veil† they even wear sexy dresses, compare before Maranao, girls are so polite and shyly, you can see them everywhere. But now, Maranao girls are so careless in their moves. They even hang out with boys. Before having a special relationship (boyfriend/girlfriend) is not allowed to the Maranao culture. You can be with the person you unless you are married. Parental is being followed by the Maranao people before, it’s a tradition but now parents actually had given the freedom to their children/ child to choose the person whom they want to be with. As generation pass by, maranao people seems to forget some of their practices like playing kulintang or other Maranao instruments. Nowadays, we can safely say that only 3 out of 10 Maranao teenagers are willing to learn Maranao practices (like playing kulintang or dance kapamalong malong, singkil, and etc. ) they chose to learn modern dances, and play instruments like guitars, drum, piano, and etc. which is a lot of different from before. IV. RESURLT ACCORDING TO SURVEY Based on our research, this is the result of the following question answered by the Maranao youth. These will show their opinions about how the modern life affects the moral value of Maranaos. Questions have shown by chart to clarify the percentage of the majority answers by the interviewees. 1. Has the modern life effect the moral value of the Maranaos? One of our basic questions was how the modern life effects the moral value of the Maranaos. The chart below shows the answer percentage of the youth we had surveyed, 90% of them answered yes while only 10% answered no. Obviously, the major answer is saying that the modern life is usually affecting the moral value of the Maranao culture. 2. Does it ruin some of the Maranao customs? Secondly, is a question about how does the modern life ruin some of the Maranao customs, 80% of them answered yes while 20% answered no. Therefore, the major answer is saying that the modern life ruin some of the Maranao customs. 3. Do you think wearing hijab nowadays matter? The question about how wearing hijab nowadays matter, 50% of the Maranao youth answered yes and the same 50% also answered no. Therefore, the result is averagely fair for the people. 4. Do you think Maranao women care for how they are treated now in the society? Base on the chart below, the pole is saying that most of the Maranao women do not care on how they are treated now in the society. 5. Do you think the Maranao youth today still knows the rituals practiced by the ancestors? 6. Do you think the modern world greatly increases the possibility for the Maranao youth to change? Another question was asking the youth if there is a possibility for Maranao youth to change. Majority answered yes, there still a chance for maranao to change while only 40% said no. 7. Do you think still some of the generation today knows how to dance Maranao tribal dances? The ideas of the youth we had interviewed emphasized on the chart below that the generation today mostly do not know how to dance the Maranao tribal dances. 8. Do you think the generations of today are interested in participating how to use maranao instrument? The same as in the question no. 7, the majority answer of the youth is no. Generation today is not interested in participating how to use maranao instrument. 9. Do you think the generation of today also cares about studying how the industry of maranao arts and crafts work? Another one, the answer of the youth on our question â€Å"do you think the generation of today also cares about studying how the industry of Maranao arts and crafts work† is no. Meaning, it is true that most of the Maranaos today is not interested studying the Maranao arts and crafts. V. CONCLUSION Therefore, Maranao culture was affected by this life changing. Through temptation and imitations, Maranaos are easily attracted to other things that can cause of this affection unlike the recipes, fashion, and style in Maranao culture little by little forgotten it. And also influenced by the new technology not only modern technology that we influence others but we do dress we have forgotten its own tradition in fashion and as well as the behaviors. Nowadays they should be aware to this problem. Unfortunately, protect our culture while not too late, apparently, because we have neglected our culture to what we see in others. This way it will not completely forget the customary tradition.

Employee Rights in the Workplace Worksheet Essays - Free Essays

Employee Rights in the Workplace Worksheet Essays - Free Essays University of Phoenix Material Employee Rights in the Workplace Worksheet Complete each section below. Be sure to cite your sources when necessary (including all uses of the textbook). 1.Laws affecting employee rights Identify three laws that affect employee rights. Include a description and the impact each has on a Human Resource Manager. LawDescriptionImpact it has on HRM Fair Labor Standards Act (FLSA)Establishes the amount of the federal minimum wage, which is revised on a periodic basis. Also require all covered employees to be paid overtime for any hours worked over 40 in a workweek.HR should constantly review the amount paid to employees. Hr managers should also ensure employees are classified appropriately for their positions, failure to comply with FLSA can lead to penalties and back pay, Americans with Disabilities ActProhibits an employee from discriminating against employees on the basis of disability or perceived disability.Hr must train managers on what information they should, or should not, require regarding an employees medical situation. The federal Family and Medical Leave Act (FMLA)Provides eligible employees with the ability to take up to 12 weeks of unpaid leave in a 12-month period for a variety of circumstances.HR managers need to be trained on the eligible reasons for leave. 2.Employee rights issues What are three current issues regarding employee rights in the workplace? Explain each and provide examples. IssueExplanationExample Age DiscriminationUnequal treatment due to his or her ageAn employee being denied a promotion or project because employee is over 40, but work shows they are equal or better than younger employees. DiversityRacial discrimination, unequal treatment due to ones ethnic background or skin colorRacial discrimination in the work place often consists of derogatory statements, unfair policies, dismissals and conditions of employment. ReligionReligious discrimination is the unequal treatment of employees based on their religious beliefs. Usually consists of unwarranted dismissals, harassment, segregation or unequal pay. An employee being forced to not actualize his religious beliefs in the workplace. 3.Employee Discipline Identify at least five factors that should be considered when disciplining an employee. 1.Seriousness of the problem 2.Duration of problem 3.Frequency and mature of the problem 4.Extenuating Factors 5.Degree of socialization Identify three best practices to use before disciplining an employee. 1.Check the handbook 2.Get the facts before taking action 3.Maintain a record 4.Personal Experience What personal experience do you have that relates to any of the above? Be specific in the situation, but do not use names or the company name. I personally have experienced age discrimination in the work place. Mostly today you hear about companies discriminating against employees over 40 because they want younger employees that are more up to date on education and technology. For me I had the opposite experience. I worked at a store that got bought out and the new owner slowly started cutting back all the employees hours that were in high school and hiring only new employees in college. He eventually one by one fired all employees that were in high school for absurd reasons. It was unprofessional and not fair to any of us that worked very hard.

The Effective Manager Assignment Example | Topics and Well Written Essays - 2250 words

The Effective Manager - Assignment Example The Effective Manager At the same time, seventy five percent (up from 50 percent the previous year) reported downtime due to security breaches. (McClure, 2003) Of those with written policies, most of them failed to adequately address security issues. When asked why they do not have policies, many answered that they do not like writing them or that they do not want to commit in writing to upholding and enforcing them. Security management is not only technology specific but for to do three things for a company: It is known that accounting, as the word implies, is a reckoning of the financial outcomes of an entity between those who control the employment of capital or assets and those who provide the capital or assets so the understanding of accounting helps managers maintaining effective security management. Accounting reacts to the needs of business and follows developments in commercial activity. One main purpose of accounting is to fairly represent the financial results of an operation to the shareholders, who are the individual owners of a business entity. In simpler words, financial profit or loss is the revenue less the cost of goods sold less the fixed or overhead costs, less interest, taxes, and an allowance for depreciation on fixed assets. Depreciation is keyed to a phase of time that sufficiently reflects the useful life of the asset while it is under the stewardship, or control, of management. If an asset under the control of management is expected to have a useful life of twelv e years, then it is usually written off, or depreciated, at 15 percent per year. Effective management is judged on its presentation to generate a profit on an asset under their control for ten years before it has to be replaced by charging management 15 percent of its value per year. Because the computation of taxes follows the same general format as reporting profits, some feel that pretax profit indicated in a financial report should be the same as the profits reported to the tax authority. In a few countries, such as Finland, Germany, Italy, Portugal, and Switzerland, this conclusion is correct. In most others, it is not. One reason for this is that the allowance for depreciation for reporting financial results may not be the same as the allowance for depreciation for filing a tax return. Whereas the purpose of financial reporting is to fairly represent the financial results of management's stewardship of the shareholders' assets, the purpose of filing a tax form is to calculate a liability. The depreciation plan selected for calculating taxes to be paid to a tax authority is the applicable schedule of depreciation decided on by the tax authority. (Kathryn, 1998) The resulting profit is severely for the computation of taxes, not to judge the performance of eff ective management to generate a pro

Vincent van Gogh Essay Example | Topics and Well Written Essays - 750 words

Vincent van Gogh - Essay Example Vincent van Gogh lived in the period 1853-1890 and died after shooting himself in the chest at the young age of 37. In spite of the fact that he was a late starter (as aforementioned, he commenced his career as an artist at the age of 27), he was highly prolific and produced more than 2000 paintings in the last 10 years of his life. The style of Vincent van Gogh is very unique but it can be best described as post-impressionist [3]. This style was initiated as an extension of impressionism but, at the same time, a rebellion against its limitations. The use of vibrant colors, thick brushstrokes and real-life subjects were features shared with impressionism. Conversely, the emphasis of geometric forms, the distortion of reality to create an emotional effect and the unnatural use of color were novel and innovative features that allowed the subsequent development of this style into expressionism, of which van Gogh was a pioneer [4, 5]. "Looking at the stars always makes me dream . Why, I ask myself, shouldn't the shining dots of the sky be as accessible as the black dots on the map of France ...., we take death to reach a star" [5]. It was perhaps this kind of thought that urged van Gogh to paint "the Starry Night" (Saint Rmy, June 1889), one of his most iconic paintings. It is oil on canvas and it is currently housed (since 1941 it is part of the permanent collection) in the Museum of Modern Art of New York (New York, USA) [5]. The tree in the painting is a cypress, a species generally associated with cemeteries and mourning. It is in the shape of a flame and helps connect heaven, represented by a lively, striking and vibrant sky, with earth, represented by the little village at the bottom of the painting. At the same time, the village identifies order, while the stars in the sky are a explosion of colour and energy. Although some critics maintain that the village depicted in the painting is not real, others believe it represents views of Saint Rmy (Provence, France) from the neighbourhood of the asylum Van Gogh was confined to at the time the painting was made. This period is often referred to as "the Saint Rmy period". It is characterised by the use of thick, sweeping brushstrokes to create a sea of swirls and spirals, which revealed the mental turmoil he was suffering. The mental hospital was housed in a former monastery a mile and a half out of town, in a area of cornfields, olive trees and vineyards. His time at the hospital gave him the opportunity to reflect about his childhood and the values and beliefs from this time of his life. The church spire is an addition that is believed to be a reference to his childhood and his native land, the Netherlands [6]. The painting favours feeling, emotion and energy and puts aside the impressionist doctrine of truth to nature. However, Van Gogh was never very happy with the painting as he considered it a study, not a finished piece. As he

Qantas Case Study Essay Example for Free

Qantas Case Study Essay It is the world’s second oldest airline, and has a successful history to uphold. Over the next 5 years Qantas aims to hedge fuel prices and use more efficient aircraft to limit further fuel costs improve employee/employer relationships by reducing the number of employment relations disputes and retain corporate market share by enhancing facilities and lounges to appeal to corporate travellers. Change management is viewed by   Alan Joyce as a critical component Reasons for current business planning What were the critical factors that led to Qantas’ decision to move some of their operations off shore? 3 2. What then happened once the decision was made4 – What change management processes needed to have taken place? 4 Were the change management processes well managed? 4 What could they have done better to counteract the disgruntled union and workers? 4 3. Where is Qantas now in its competitive positioning both locally and internationally?

Understanding OPEC: An Economic Analysis Essay -- Oil Economics Econom

Understanding OPEC: An Economic Analysis In the last few months, much has been said of Iraq’s invasion of Kuwait in 1990. Interestingly enough, one of Iraq’s motivating factors was economics. Kuwait provided Iraq with a pretext for war as it violated the economic policies of the Organization of Oil-Exporting Countries by exporting oil above its quotas. This is but one chapter in the complicated history of OPEC. OPEC is an international assembly of nations which co-ordinates and unifies the petroleum policies of eleven countries and has enjoyed the highs and weathered the lows of oil prices in the last few decades. To solve their problems, both member countries and oil-importing countries must address the complex nature of oil price elasticity in making their policy decisions. An analysis of OPEC’s policies demands a cursory review of its history and the recent and current structure of the oil market. Acting in concert, OPEC’s eleven member countries set per country quotas for oil production to limit the oil supply. It seeks to â€Å"co-ordinate and unify their petroleum policies in order to promote stability and harmony in the oil market† (OPEC 2). In other words, OPEC seeks to secure a long-term profitable stream of income for OPEC members by exploiting its market power in an oligopoly. OPEC has commanded tremendous market power in the oil industry ever since Iran, Iraq, Kuwait, Saudi Arabia and Venezuela founded it on September 14, 1960. Today, the number of member countries has risen to 11 and now includes Algeria, Indonesia, SP Libyan AJ, Nigeria, Qatar, and the United Arab Emirates. Together, these countries have pooled their tremendous resources: â€Å"OPEC Members Countries produce about 41 per cent of the world’s crude oi... .... 2000. Organization of the Petroleum Exporting Countries. 19 April 2003 . Answers to frequently asked questions about the petroleum industry. 2000. Organization of the Petroleum Exporting Countries. 19 April 2003 . Foreman, Gary. Use the â€Å"Law† to Save Thousands. Soho America. 19 April 2003 www.soho.org/Finance_Articles/Spply_and_Demand.htm. Hwang, M. J. and C. W. Yang. Unstable Price Elasticity and High World Oil Prices. October 2001. The 52nd International Atlantic Economic Conference. 19 April 2003 < www.iaes.org/conferences/past/philadelphia_52/prelim_program/d00-1/index.htm>. Taylor, Jerry. No Need to Panic over Oil Prices: Don’t Believe the Politicians’ Rhetoric. 2003. Cato Institute. 19 April 2003 .

Review of the Efficacy of the Picture Exchange Communication

J Autism Dev Disord (2009) 39:1471–1486 DOI 10. 1007/s10803-009-0763-y ORIGINAL PAPER A Review of the Ef? cacy of the Picture Exchange Communication System Intervention Deborah Preston ? Mark Carter Published online: 3 June 2009 O Springer Science+Business Media, LLC 2009 Abstract The Picture Exchange Communication System (PECS) is a communication program that has become widely used, especially with children with autism. This paper reports the results of a review of the empirical literature on PECS. A descriptive review is provided of the 27 studies identi? d, which included randomized controlled trials (RCTs), other group designs and single subject studies. For 10 appropriate single subject designs the percentage of nonoverlapping data (PND) and percentage exceeding median (PEM) metrics were examined. While there are few RCTs, on balance, available research provides preliminary evidence that PECS is readily learned by most participants and provides a means of communication fo r individuals with little or no functional speech. Very limited data suggest some positive effect on both socialcommunicative and challenging behaviors, while effects on speech development remain unclear.Directions for future research are discussed including the priority need for further well-conducted RCTs. Keywords Picture exchange communication system A Augmentative and alternative communication A Autism Introduction Serious de? cits in communication form part of the primary diagnostic criteria for autism (American Psychiatric Association 2000). It has been estimated that around D. Preston A M. Carter (&) Macquarie University Special Education Centre, Macquarie University, Sydney, NSW 2109, Australia e-mail: mark. [email  protected] edu. au one-third to one-half of children and adults with autism do not have unctional speech (Mirenda 2003). Such individuals may show only pre-intentional communication, such as reaching for a desired item, or communication may demonstrate intent through behaviors such as alternating eye gaze, and conventional gestures such as pointing (Yoder et al. 2001). Communication may also take the form of challenging behaviors (Mirenda 1997). When speech does develop it may be limited mainly to unusual or echolalic verbalizations (Paul 2005). Individuals with serious developmental disabilities other than autism may also fail to develop speech and language skills (Westling and Fox 2004).In order to help develop communication skills, various forms of augmentative and alternative communication (AAC) have been developed. These include the use of manual signs (e. g. , Layton 1988; Yoder and Layton 1988), voice output communication devices (VOCAs) (reviewed by Lancioni et al. 2001), and various picture-based systems (Keen et al. 2001; Sigafoos et al. 1996). The Picture Exchange Communication System (PECS) is a picturebased system developed by Bondy and Frost (1993, 1994) to help young children with autism acquire functional communication sk ills. PECS appears promising for several reasons.First, it avoids dif? culties inherent in other systems by requiring very few prerequisites; in fact the only prerequisite is that the individual can clearly indicate (e. g. , by reaching for an item) what he or she wants, in a way that can be shaped into exchanging a physical symbol such as a picture (Bondy and Frost 2002). Other skills such as eye contact, motor or verbal imitation skills, the ability to sit quietly in a chair, match-to-sample skills, picture discrimination, or the ability to follow verbal prompts are not necessary (Bondy and Frost 1994, 2002), at least at the earliest program stage. 23 1472 J Autism Dev Disord (2009) 39:1471–1486 Second, the ? rst skill taught in PECS is requesting. Requesting has often been targeted in early instruction of individuals with developmental disabilities due to motivational considerations (Reichle and Sigafoos 1991). In relation to PECS, it is argued that individuals with autism in particular are less likely to be motivated by the social consequences of labeling or commenting (Bondy and Frost 1995) and more likely to be motivated by requesting and immediately obtaining a speci? c, typically concrete, desired item (Bondy and Frost 1994).Third, PECS systematically addresses the issue of spontaneity, which has often been reported as problematic in individuals with autism spectrum disorders (ASD) (Chiang and Carter 2008; Koegel 2000). Rather than being dependent on a partner to establish a communicative exchange, or requiring a partner to watch for the learner to point to a picture board or generate a manual sign, which could easily be missed, PECS speci? cally teaches the individual to approach the partner and gain their attention by putting a picture symbol into their hand.Fourth, picture symbols can be highly iconic, closely resembling their referents (Ganz and Simpson 2004; Mirenda 2003). Consequently, they may be easily recognized by the learner (Ganz and Simpson 2004) and are more recognizable by communicative partners than some other systems, such as manual signs (Lancioni et al. 2007). The PECS protocol begins with a reinforcer assessment through which the trainer determines an ordered list of reinforcers for the individual (Bondy and Frost 1998). This is followed by six phases, which are brie? overviewed in Table 1. For each phase, the criterion for successful completion is 80% or more trials successful without prompting in a 10-trial block (Charlop-Christy and Jones 2006). The randomized control trial (RCT) is recognized as providing the gold standard for evaluating clinical interventions in areas such as medicine and education (Evidence-Based Medicine Working Group 1992; What Works Clearinghouse 2006) and ideally evaluations would be limited to such evidence (Carter and Wheldall 2008).Such designs, however, are relatively rare in educationrelated areas (Carter and Wheldall 2008) for a variety of reasons and clinicians must oft en look to a second line of evidence to inform decision-making. Single subject quasiexperimental designs employ repeated measures of the dependent variable over time with a single or small number of participants. Although not offering the standard of evidence of RCTs, the best of these designs are considered capable of effectively controlling major threats to internal validity and strong conclusions about causal inference can be drawn (Campbell and Stanley 1963; Horner et al. 005). Similarly, high quality quasi-experimental group designs, speci? cally those involving non-equivalent groups with pre-test matching, are generally considered to be interpretable (Flay et al. 2004). The weakest level of evidence is provided by pre-experimental designs, such as single group pre-test—post-test studies, where few threats to internal validity are controlled and causal inference cannot be inferred with any degree of con? dence (Campbell and Stanley 1963). Early papers on PECS were largel y descriptive with limited data (e. . , Bondy and Frost 1993, 1994, 1995, 1998), or presented outcome data without control (e. g. , Schwartz et al. 1998). In recent years, however, a number of interpretable group studies (e. g. , Yoder and Stone 2006b) and single subject studies (e. g. , Charlop-Christy et al. 2002; Tincani 2004) have been published. Lancioni et al. (2007) reviewed the use of PECS and VOCA (voice output communication aids) for request making in individuals with developmental disabilities. In addition to studies following the PECS protocols of Frost and BondyTable 1 Summary PECS stages Phase Teaching target I II Make requests through picture exchange Persistence in initiating communication Discrimination between symbols Introduction of sentence structure Answering question with a request Commenting Description Second person acts as a prompter from behind learner; when learner reaches for the desired item, physically prompts to exchange picture; prompts faded as quick ly as possible Communicative partner moves gradually further away; picture is also gradually moved further away; number of communicative partners increased; ‘‘Communication book’’ is introduced; range of items requested is increased, but only one picture and item is available at a time Initially, two pictures are presented (highly preferred and neutral or disliked); more pictures are added; later, more than one preferred item is offered at a time; periodic correspondence checks are carried out to check accuracy at discrimination Taught to use a sentence strip, placing an ‘‘I want’’ as well as the symbol; requests can also be expanded with attributes such as color or size, e. g. ‘‘I want red playdough’’ Taught to answer question ‘‘What do you want? ’’ Taught to respond to other simple questions such as ‘‘What do you see? ’’; gradually, more spontaneous com menting is developed III IV V VI 123 J Autism Dev Disord (2009) 39:1471–1486 1473 (1994, 2002), they also included studies employing ‘‘any conventional use of pictorial material as a way of making requests for preferred items’’ (p. 4).Thus, studies that did not follow PECS protocols, and in which the participants pointed to a picture rather than actually exchanging it, were included (e. g. , Dyches et al. 2002; Keen et al. 2001). In addition, no attempt was made to quantify the data obtained from the studies to evaluate either the overall ef? cacy or effectiveness of the approach or the effect of relevant variables on outcomes. To date, no comprehensive review of empirical literature speci? cally examining the PECS approach of Frost and Bondy (1994, 2002) appears to have been published. The present paper looks speci? cally at studies of PECS intervention as described by Frost and Bondy (1994, 2002).In the absence of a substantial number of gold-stand ard RCT studies that would allow a conventional meta-analysis, a broader approach to evaluation of the research was undertaken. This review is intended to examine the extant empirical research on PECS, with speci? c consideration of the research designs employed and, consequently, the strength of conclusions that can be drawn. excluded (e. g. , Son et al. 2006). One article in which previously taught communication using the PECS program was compared to facilitated communication (Simon et al. 1996) was excluded because there was no PECS intervention during the study. The study of Rosales and Rehfeldt (2007), in which the ? rst three phases of PECS was taught prior to the experiment, was lso excluded because no data on the results of the PECS training was provided. Analysis A summary of each study was prepared including participants, research design, treatment and duration of study, outcomes investigated, setting, PECS version and phases implemented, and a summary of the outcomes, as well as inter-observer and procedural reliability, social validity, maintenance and generalization data. Ages of participants were coded into 5, 5–8, 9–17, or over 18 years. Four categories of dependent variable were identi? ed: PECS exchanges (number or percentage of independent exchanges), speech or vocalization, social-communicative behaviors, and undesirable behaviors.As the majority of studies employed single subject designs, they were coded for quality using an adaptation of the guidelines for single subject research presented by Horner et al. (2005). These indicators addressed several areas: adequacy of participant and setting descriptions; dependent variables; independent variables; baseline; experimental control/internal validity; external validity; and social validity. A total of 10 points were allocated to each area with the exception of external validity, which was allocated 5 points in recognition of the inherent limitations of single subject designs in th is regard. Thus, studies were rated on a scale from 0 to 65, with higher scores indicating greater quality.Details of the criteria are included in the Appendix. Traditionally, single subject studies have been interpreted by visual inspection of graphed data (Reynhout and Carter 2006). More recently, attempts have been made to quantify results of these studies objectively, and to provide reliable data summaries for evaluating evidence-based interventions (Parker et al. 2007). The most commonly used of the resulting statistical indices is the percentage of non-overlapping data (PND) (Scruggs et al. 1987). The PND is the percentage of treatment data points that are above (or below when behavior decrease is targeted) the highest (or lowest) baseline data point.Scruggs and Mastropieri (1998) provided guidelines for the interpretation of PND: scores between 91 and 100 indicate highly effective interventions, between 71 and 90 effective interventions, between 51 and 70 questionable interve ntions, and 50 or below ineffective interventions. Whilst PND has been criticized on a number of grounds (e. g. , Allison and Method Search Strategy Empirical studies using PECS were identi? ed through computerized searches of A? Education, British Education Index, ERIC, Expanded Academic ASAP, Linguistic and Language Behavior Abstracts, PsycINFO, PubMed and ScienceDirect, using the descriptors ‘‘PECS’’ or ‘‘Picture Exchange Communication System’’. In addition, manual searches of the reference lists of articles identi? ed were carried out to locate further studies.Studies were included if they: (1) (2) were journal articles in English from 1992 to July 2007; used PECS (Bondy and Frost 1994; Frost and Bondy 1994, 2002) as whole or part of an intervention strategy as indicated by reference to program documentation and description of implementation; presented group or individual data on the results of the intervention. (3) Articles th at referred to PECS but did not follow Frost and Bondy’s protocol were excluded. For example, Dooley et al. (2001) used a ‘‘PECS-based schedule board’’ (p. 58) but no actual picture exchange. In addition, articles that used a picture exchange system but did not speci? cally stated that the PECS protocols (Bondy and Frost 1994; Frost and Bondy 1994, 2002) were employed were 123 1474 J Autism Dev Disord (2009) 39:1471–1486 Gorman 1993; Salzberg et al. 1987; White 1987), it is nevertheless the most widely used statistic for quantifying data from single subject studies (e. g. Bellini and Akullian 2007; Erion 2006; Lee et al. 2007; Reynhout and Carter 2006; Xin et al. 2005). A particular disadvantage of PND is that if any baseline data point has reached the ceiling or ? oor level of the measurement scale, the calculated PND is 0%, even if visual inspection indicates a treatment effect (Ma 2006). Ma (2006) has suggested an alternative, the percentag e of data points exceeding the median (PEM). The PEM is the percentage of treatment data points that are above (or below when behavior decrease is targeted) the median baseline data point. There is also evidence that PEM may correlate better with author judgments of program ef? cacy than PND (Ma 2006).Nevertheless, PND is by far the most widely used metric for summarizing single subject studies and comparative data are available on a range of interventions. The application of the PEM statistic is very limited to date but, given its potential advantages, it was decided to calculate both PEM and PND values in the current review. It has also been argued that con? dence in ? ndings from analysis of single subject studies may be strengthened if multiple approaches to synthesis converge on similar conclusions (Smoot et al. 1990). PND and PEM statistics were calculated for all single subject studies with graphed data including a baseline and intervention phase. Changing conditions (i. e. , PECS phase changes), were coded as part of the ‘‘intervention’’ phase.Metrics were initially calculated for treatment data only and then for all intervention data, including treatment, maintenance and generalization phases. The PND statistic was calculated for each study using the pooled number of non-overlapping data points across all subjects and categories of dependent variable (PECS exchanges, speech/ vocalization, social-communicative behaviors, undesirable behaviors). In addition, a PND statistic was calculated for each participant and for each category of dependent variable within relevant studies. Similarly, PEM statistics were calculated using the pooled number of data points exceeding, or below when appropriate, (i. e. , for undesirable behavior) the baseline median.In cases where the exact value of data points on a graph was dif? cult to determine, a copy of the graph was obtained from a Portable Document Format copy of the article or a good qua lity digital scan. Subsequently, numeric data were extracted using the Digitizelt (Bormann 2003) computer software. Inter-Rater Reliability PND and PEM values were independently calculated by the ? rst and second authors for ? ve randomly selected single subject studies (50% of studies for which calculation was possible). Values were calculated for each graph that included a baseline and time-series data. Where more than one panel was shown on the same graph (e. g. multiple baseline, alternating treatments), a value was calculated for each panel. For each panel, reliability was calculated by dividing the lower percentage value by the higher percentage value and multiplying by 100 (i. e. , if both raters agreed on the percentage value, the reliability was 100%). The same ? ve studies were independently rated for quality indicators by the ? rst and second authors. Inter-rater reliability was calculated by dividing the number of agreements by the total of agreements and disagreements, and multiplying by 100. Inter-rater reliability for both PND and PEM was 100% for 54 panels and over 90% for the remaining three panels with an overall mean agreement of 99. 8%.There were discrepancies in only three graphs; the majority of these related to determining how many data points were present in very small ? gures. Inter-rater reliability for quality indicators was 97. 5%. Results A summary of the participants, research design, inclusion of maintenance or generalization data, PECS phases taught, and outcomes examined is presented in Table 2. Research Design The early studies (Bondy and Frost 1993, 1994, 1998; Schwartz et al. 1998) were all reports or program evaluation data without adequate experimental control, as were two later studies (Liddle 2001; Webb 2000). Malandraki and Okalidou (2007) used a case study.Magiati and Howlin (2003), in their pilot study, used a pre-PECS treatment measure plus three measures over time, with data mainly from teacher ratings. All of these studies can be considered pre-experimental. Of the 14 single subject studies, 4 used alternating treatments. Adkins and Axelrod (2001), Chambers and Rehfeldt (2003) and Tincani (2004) compared PECS and manual signing, while Bock et al. (2005) compared PECS and VOCA (voice output communication aid). Four studies (Charlop-Christy et al. 2002; Rehfeldt and Root 2005; Tincani et al. 2006, Study 1; Yokoyama et al. 2006) used a multiple baseline across participants, while two (Frea et al. 2001; Kravits et al. 2002) used a multiple baseline across settings, one (Marckel et al. 006) used a multiple baseline across descriptors taught, and one (Cummings and Williams 2000) used a multiple baseline across activities. Two studies (Stoner et al. 2006; Tincani et al. 2006, Study 2) used an ABAB design, while one (Ganz and Simpson 123 Table 2 Summary of Studies Ages Dependent variable Research design Maintenance (M) PECS or generalization (G) Phases data I–III I–III I–III Iâ⠂¬â€œIV I–III I–III I–III I–VI III Picture exchange, sign Picture exchange, VOCA Picture exchange Picture exchange, speech Picture exchange, speech Speech Social/communicative Picture exchange, sign language Speech, social, behavior (variation) Authors Participants DiagnosisAdkins and Axelrod (2001) – 35 Autism Autism Autism Autism Autism 1 ‘‘autistic characteristics’’ Autism 2 autism, 3 PDD 3–5 years Single-subject (multiple baseline) – 3–12 years Single-subject (multiple baseline) M,G 19–40 years Single-subject (alternating treatment) G 3–7 years 3–7 years Non-equivalent control group Non-equivalent control group – G 32 months Program evaluation – 6 years Program evaluation – 6 years– adult Program evaluation – 4 years Single-subject (alternating treatment) G 1 PDD 7 years Single-subject (alternating treatment) G Bock et al. (2005) 6 Bondy and F rost (1993) 74 Bondy and Frost (1994) 85 Bondy and Frost (1998) 1 J Autism Dev Disord (2009) 39:1471–1486 Carr and Felce (2007a) Carr and Felce (2007b) 10 41 Chambers and Rehfeldt (2003) 4 Charlop-Christy et al. (2002) 3Cummings and Williams (2000) Autism Autism Autism Autism 14 ASD Autism or ASD Autism Autism – 16 autism/PDD-NOS – 3–6 years 22–31 years 20–34 years 4–5 years 10 years Case study Single-subject (multiple baseline) Single-subject (multiple probe) Program evaluation Single-subject (ABAB) Single-subject (alternating treatment) 9–11 years Single-subject (multiple baseline, ABAB) 5–12 years Single group School Program evaluation 6 years Single-subject (multiple baseline) 3–7 years 4–11 years Single-subject (changing criterion RCT G M – – G M G – G G G G 4 years Single-subject (multiple baseline) – 5 Picture exchange, other I–III I–IV I–VI I–I II I–VI I–VI I–VI Extension I–III I–IV I–IV I–III I–IV Picture exchange, behavior Picture exchange, speech Picture exchange, speech, ADOS-G Picture exchange, speech, social Picture exchange Picture exchange, speech, other Picture exchange Picture exchange (improvised requests) Picture exchange, other Picture exchange, speech, other Picture exchange Picture exchange Picture exchange, sign, speech PECS, speech 1475 Frea et al. (2001) 1 Ganz and Simpson (2004) Howlin et al. (2007) 3 84 Kravits et al. (2002) 1 Liddle (2001) 21 Magiati and Howlin (2003) 34Malandraki and Okalidou (2007) 1 Marckel et al. (2006) 2 Rehfeldt and Root (2005) 3 Schwartz et al. (1998) 31 Stoner et al. (2006) 5 Tincani (2004) Autism 2 1 autism, 1 PDD-NOS 5–6 years 123 Tincani et al. (2006) 3 1476 J Autism Dev Disord (2009) 39:1471–1486 Maintenance (M) or generalization (G) data M,G 2004) used a within subjects changing criterion design. In seve ral studies, a changing criterion was included, re? ecting the PECS phase changes but it was secondary to the main design (Bock et al. 2005; Chambers and Rehfeldt 2003; Cummings and Williams 2000; Rehfeldt and Root 2005; Stoner et al. 2006; Tincani 2004; Tincani et al. 2006; Yokoyama et al. 2006).Comparative group designs were employed in ? ve papers. Yoder and Stone (2006a, b) used random assignment to PECS or Responsive Education and Prelinguistic Milieu Teaching (RPMT) intervention groups, while Howlin et al. (2007) used random assignment of classes to immediate treatment, delayed treatment or no treatment with PECS groups. Carr and Felce (2007a, b) used a quasiexperimental group design whereby PECS intervention and control groups were chosen by geographical location, and included both within subjects and between group measures. Pre-test equivalence of the groups was established. Participants Picture exchange, speech PECS Phases I–VI I–VI G I–VI G –Sin gle-subject (multiple baseline)) I–IV Picture exchange, speech Dependent variable Speech Social In total, there were 456 participants in the 27 studies; of these, 394 (86%) received PECS intervention and 62 (14%) were in non- or alternative-intervention groups. Of the total, 377 (83%) were described as having ASD. Ages of participants ranged from 20 months to 40 years and there were 198 males (43%) and 38 (8%) females with the gender of 220 (48%) of participants unstated. Where the same or a subgroup of participants were reported in multiple studies (Carr and Felce 2007a, b; Yoder and Stone 2006a, b), they were counted only once. The group experimental (Howlin et al. 007; Yoder and Stone 2006a, b) or quasi-experimental (Carr and Felce 2007a, b) studies involved a total of 161 participants (35% of the total sample): 98 in PECS intervention groups and 92 in control or other treatment groups. The Delayed Treatment Group in the Howlin et al. (2007) study was used as both control and intervention at different times. All these children were described as having autism or PDD-NOS and little or no speech. They ranged in age from 20 months to 11 years at study commencement. These studies all provided information on the initial abilities of the participants based on standardized tests. The single subject studies involved a total of 42 participants (9% of the total sample) and all provided information on diagnosis, age and gender.Only a minority provided information on the diagnostic instrument or protocol used to identify ASD (Ganz and Simpson 2004; Marckel et al. 2006; Yokoyama et al. 2006), described the degree of autism or provided standardized assessment data or a description of general ability for all participants (Chambers and Rehfeldt 2003; Frea et al. 2001; Kravits et al. 2002; Rehfeldt and Root 2005; Stoner et al. 2006; Research design Program evaluation 55–70 months RCT 21–54 months Autism/PDD 36 Yoder and Stone (2006a) 20–53 months Autism/PDD Yoder and Stone (2006b) 36 RCT Diagnosis Participants 6 Table 2 Summary of Studies 123 Yokoyama et al. (2006) Authors Webb (2000) 3 Autism 5 ASD 5–7 years Ages J Autism Dev Disord (2009) 39:1471–1486 1477 Yokoyama et al. 2006).Most researchers did document initial communication skills, either using standardized test results or a description of functional skills, although some descriptions were minimal. Participants were almost entirely described as non-verbal or having little or no functional speech, or in some cases no functional communication. The participants in the Marckel et al. (2006) study were able to use PECS independently to make requests at the start of the research. Participants in three studies were explicitly identi? ed by researchers as having challenging behavior (Adkins and Axelrod 2001; CharlopChristy et al. 2002; Frea et al. 2001). Interobserver and Procedural Reliability Interobserver reliability was reported for 20 of the 27 papers revie wed. Papers in which interobserver reliability was not reported included ? e earlier program evaluations (Bondy and Frost 1993, 1994, 1998; Liddle 2001; Webb 2000) and one single subject study (Adkins and Axelrod 2001). Reliability ranged from 80. 3 to 100% calculated on between 10 and 100% of data. Three studies (Howlin et al. 2007; Kravits et al. 2002; Malandraki and Okalidou 2007) estimated reliability on less than a minimum standard of 20% of total sessions. In contrast, procedural reliability was reported for only 7 of the 27 studies (Bock et al. 2005; Cummings and Williams 2000; Marckel et al. 2006; Tincani 2004; Tincani et al. 2006; Yoder and Stone 2006a, b) and discussed but not formally calculated in one other (Stoner et al. 2006). Where reported, procedural reliability ranged from 96 to 100%.In two papers (Yoder and Stone 2006a, b) less than 20% of sessions were used for the estimate. Social Validity Formal measures of social validity were reported in only four papers (Mag iati and Howlin 2003; Marckel et al. 2006; Tincani 2004; Yoder and Stone 2006a). Settings Fourteen studies were conducted in a special school, special preschool or special classroom setting. Remaining studies were conducted in a variety of settings including an integrated preschool, regular classroom, homes, clinics, day treatment facilities, and combinations of these settings. Ef? cacy and Effectiveness of PECS Of the total group of 394 individuals who received PECS intervention, only one child was reported as being nsuccessful at mastering at least phase I (Liddle 2001), and one adult had dif? culty with the motor and cognitive demands of the training and failed to progress past phase I (‘‘Mike’’, Stoner et al. 2006). ‘‘Carl’’, from Tincani’s (2004) study, was more successful with manual signs than PECS, but, the great majority successfully mastered at least some phases of PECS. Outcome data will now be considered further, initially focusing on pre-experimental designs, then single subject designs, quasi-experimental group designs and ? nally RCTs. This will be followed by a more detailed consideration of maintenance and generalization. Pre-Experimental Studies Several studies used pre-experimental designs.Bondy and Frost (1993) reported data on the implementation of PECS and found increased communicative initiations and use of pictures. Bondy and Frost (1994, 1998), Schwartz et al. (1998), Webb (2000), and Liddle (2001) also presented data on PECS implementation and reported increases in spoken language following PECS training. Schwartz et al. found that children were able to acquire communication with PECS training and there was evidence of generalization across pragmatic function. These studies, however, lacked adequate experimental control, and especially given the young age of the children involved in at least four studies, it is unknown how communication would have developed without the interve ntion.In their pilot study, Magiati and Howlin (2003) used a pre-treatment measure and three teacher ratings over time. They found signi? cant increases in PECS level (d = 2. 91),1 frequency of spontaneous use (d = 1. 75), and number of symbols used (d = 3. 01) over the 6 months following teacher training in PECS and its subsequent introduction. These are very large effect sizes by educational standards. They also found smaller but still statistically signi? cant increases in the number of signs (d = 0. 31), words (d = 0. 32) and phrases (d = 0. 30) used, and in the overall level of spontaneous communication (d = 0. 83). Outcomes were, however, measured mainly through teacher rating scales.The results must be treated with caution as they are likely to have been in? uenced by expectations and the research design was very weak. 1 For pre-test post-test designs, effect sizes were calculated by subtracting the pretest mean from the post-test mean and dividing by the pooled standard devi ation. For studies involving a comparison group, effect sizes were calculated by subtracting the mean of the control or alternate treatment group from the mean of the PECS intervention group and dividing by the pooled standard deviation. 123 1478 J Autism Dev Disord (2009) 39:1471–1486 Single Subject Studies PND and PEM statistics were calculated for the 10 single subject studies that provided baseline and intervention data.Initially, calculations were conducted on treatment data alone and then on all intervention data, including treatment, maintenance and generalization. When compared, the overall mean differences in favor of the treatment alone data were very small, only 0. 4% in the case of PND and 0. 8% for PEM. It was considered that the inclusion of all intervention data provided the best indicator of the ef? cacy of the overall package and these data were used for the remaining analysis. Results are provided in Table 3. Calculations were not possible for the four addit ional single subject studies (Adkins and Axelrod 2001; Cummings and Williams 2000; Ganz and Simpson 2004; Rehfeldt and Root 2005). These studies either lacked baseline data (e. g. alternating treatment design without baseline) or lacked baseline data that corresponded directly to that collected in intervention. The overall mean PND was 78. 5% (range 50– 100), placing the PECS intervention in the effective range (Scruggs and Mastropieri 1998). The overall mean PEM was 89. 1% (range 72. 3–100). Quality indicator scores are also presented in Table 3, and ranged from 30. 6 to 55. 7 out of a possible 65 points. Correlation between Quality Indicator scores for each study and their associated study PND was not signi? cant (rs = -0. 05, p = 0. 87). For PEM there was a trend toward weaker studies producing higher effect sizes but this did not reach signi? cance (rs = -0. 44, p = 0. 19).Mann–Whitney U tests or Kruskal–Wallis one-way ANOVAs were used to compare PND and PEM values across participant and study characteristics and these data are presented in Tables 4 and 5. No signi? cant difference in PND was found for age, gender, setting, inclusion of maintenance or generalization data, or research design. A signi? cant difference was found for PND scores for outcome variables, with studies addressing picture exchange only having a higher mean PND than those that included other dependent variables (i. e. , speech, social, behavioral, with or without picture exchange). A signi? cant difference was also found between PND values for participant diagnosis.Post hoc comparison showed that PND for children identi? ed with autism (i. e. , autistic disorder) were signi? cantly lower than for the other two groups, but these groups were not signi? cantly different from each other. No signi? cant difference was found between PEM values for any of the study or participant characteristics although participant diagnosis approached signi? cance (p = . 06). Fo ur of the single subject studies included data speci? cally relating to speech development from which PND and PEM values could be calculated (Charlop-Christy et al. 2002; Tincani 2004; Tincani et al. 2006; Yokoyama et al. 2006). The mean calculated PND was 49. % (range 19. 5– 100) and PEM 54. 2% (range 25. 0–100). These values are in the non-effective or at best very mildly effective range but with wide variation. Charlop-Christy et al. (2004) found increases in speech during PECS training. Tincani (2004) examined independent word vocalizations during PECS and sign language training. The addition of a Table 3 Single subject studies: PND and PEM results; study quality results Study PND PEM Study quality (Maximum 65) Picture Speech Social Behavior Overall Picture Speech Social Behavior Overall exchange exchange Adkins and Axelrod (2001) Bock et al. (2005) Chambers and Rehfeldt (2003) Charlop-Christy et al. 2002) Cummings and Williams (2000) Frea et al. (2001) Ganz and Si mpson (2004) Kravits et al. (2002) Marckel et al. (2006) Rehfeldt and Root (2005) Stoner et al. (2006) Tincani (2004) Tincani et al. (2006) Yokoyama et al. (2006) Mean SD – 92. 1 100. 0 – – 100. 0 – 87. 7 97. 3 – 77. 5 90. 6 98. 6 68. 7 90. 0 10. 9 – – – 59. 8 – – – – – – – 100. 0 20. 0 19. 5 49. 8 38. 4 – – – 86. 8 – – – – – – – – – – 86. 8 n/a – – – 26. 0 – 0 – – – – – – – – 13. 0 18. 4 – 92. 1 100. 0 55. 6 – 50. 0 – 87. 7 97. 3 – 77. 5 95. 3 70. 5 58. 6 78. 5 18. 8 – 92. 1 100. 0 – – 100. 0 – 87. 7 100. 0 – 90. 1 90. 6 98. 6 89. 9 94. 3 5. 2 – – – 65. 7 – – – – – – – 100. 0 25. 0 26. 0 54. 2 36. 0 – – – 95. – – – – – – – – – – 95. 6 n/a – – – 85. 0 – 100. 0 – – – – – – – – 92. 5 10. 6 90. 1 95. 3 72. 3 76. 7 89. 1 10. 6 – 92. 1 100. 0 76. 3 – 100. 0 – 87. 7 100. 0 30. 6 55. 7 43. 8 52. 4 32. 9 42. 4 35. 3 50. 4 49. 6 43. 8 50. 3 48. 2 45. 7 50. 3 45. 1 7. 6 123 J Autism Dev Disord (2009) 39:1471–1486 Table 4 Means, standard deviations and Mann–Whitney U test results for PND and PEM scores of study and participant characteristics Variable N PND M (SD) Quality indicators C50 50 PECS only Includes other Yes No 5 74. 3 (16. 6) 5 82. 6 (21. 7) 5 90. 9 (8. 9) 5 66. 0 (18. 0) 3. 0 0. 94 84. 6 (7. 5) 93. 5 (12. 0) 3. 0 1. 98* 94. 0 (5. 7) 84. 1 (12. 6) 7. 0 1. 14 5. 0 1. 6 U z PEM M (SD) U z Research design Multiple baseline Alternating treatments ABAB A ge Under 5 5–8 2. 0 1. 56 76. 5 (0. 3) 92. 2 (9. 4) 4. 0 1. 04 87. 9 (11. 2) 93. 9 (8. 7) 6. 0 1. 27 89. 9 (12. 2) 11. 0 0. 21 88. 5 (10. 5) 88. 5 (12. 5) 52. 0 0. 46 92. 5 (11. 2) 6. 0 0. 52 2. 0 1. 56 9–17 18? Diagnosis Autism PDD-NOS/autistic characteristics Other Setting Special school/ preschool Clinic Integrated preschool Home Combination 10 1 1 9 8 90. 1 (12. 5) 3. 87 79. 3 (n/a) 50. 0 (n/a) 74. 3 (30. 4) 82. 3 (21. 8) 2 57. 1 (2. 1) 8 83. 8 (17. 0) 9 8 3 9 13 85. 0 (17. 0) 2. 58 73. 1 (31. 2) 72. 2 (21. 4) 87. 9 (18. 5) 69. 8 (25. 9) 7. 68* 93. 8 (7. 3) 84. 4 (11. 4) 75. 4 (18. 8) 93. 5 (11. 1) 6 3 1 70. 0 (19. 0) 3. 82 95. 8 (4. 0) 77. 5 (n/a) 479 Table 5 Descriptive statistics and Kruskal–Wallis One-Way ANOVA results of PND and PEM scores of study and participant characteristics Variable N PND M (SD) H PEM M (SD) H 85. 5 (12. 3) 1. 62 95. 8 (4. 0) 90. 1 (n/a) 6. 74 Outcome variables Maintenance data included Generalization data included Yes 8 80. 9 (17 . 8) No Yes No Gender Male Female 2 68. 9 (26. 7) 4 88. 8 (12. 4) 6 71. 6 (20. 0) Procedural reliability data 83. 7 (13. 2) 5. 59 100. 0 (0) 92. 8 (9. 8) 90. 4 (11. 8) 2. 29 79. 3 (n/a) 100. 0 (n/a) 87. 8 (13. 1) 89. 2 (13. 4) 2 100. 0 (0) 14 89. 2 (15. 2) 25 78. 9 (23. 9) 40. 5 1. 12 5 92. 5 (11. 2) Note: * Indicates signi? cant result at 0. 05 level for two-tailed test reinforcer delay in phase IIIb resulted in increased in word vocalizations. Tincani et al. 2006) examined word vocalizations and vocal approximations during PECS training, and found a decrease during phases I-III before dramatic increases in phase IV. In a second experiment, looking at phase IV only, a higher percentage of word vocalizations was found with the reinforcement delay procedure than without. Yokoyama et al. (2006) examined frequency and intelligibility of vocalization during PECS training in phases I-IV; these authors also found an increase with the time delay procedure. Several other studies provided da ta on speech development, which was not suitable for calculation of PND or PEM values. Kravits et al. (2002) found an increase in frequency of intelligible speech but not in range of spoken vocabulary.Ganz and Simpson (2004) found that words per trial increased noticeably during phase IV or phases III and IV of PECS training, in particular, simultaneously with delayed word modeling. Charlop-Christy et al. (2002) provided the only appropriate data for calculation of PND and PEM values for social outcomes. From this very small amount of data, the PND of 86. 8% and PEM of 95. 6% suggest an effective or highly effective intervention. Variables that increased in this study were eye contact, joint attention, cooperative play, and frequency of initiations and requests including but not limited to PECS requests. Initiations and requests Note: * Indicates signi? cant result at 0. 05 level for two-tailed test ncreased the most, and joint attention also increased in all three children. It has been suggested that a direct positive relationship exists between joint attention and communication in children with autism, with improvement in one potentially stimulating an increase in the other (CharlopChristy et al. 2002). Kravits and colleagues (2002) reported some increase in duration of social interaction with peers although these data were not suitable for calculation of PND or PEM as only the mean level in each phase was presented. PND and PEM scores were calculated for data from only two studies for behavioral variables (CharlopChristy et al. 2002; Frea et al. 2001). The mean PND was 13. 0% while the mean PEM was 92. %, but, examination of graphed data showed treatment effects, indicating that decreased problem behaviors occurred in conjunction with increased communication skills through PECS training. Two studies compared sign language to PECS interventions (Chambers and Rehfeldt 2003; Tincani 2004) and one compared a VOCA to PECS (Bock et al. 2005). For each of these st udies PND and PEM were equal, and a higher value was found for PECS than for the alternative intervention. For Tincani (2004) calculated values were 95. 3% for PECS and 92. 3% for sign, for Chambers and 123 1480 J Autism Dev Disord (2009) 39:1471–1486 Rehfeldt (2003) values were 100% for PECS, and 65. 7% for sign, and for Bock et al. 2005) values were 92. 1% for PECS and 79. 7% for VOCA. Quasi-Experimental Group Studies Carr and Felce (2007b) found signi? cant improvement in several aspects of communicative interaction between children and staff following 15 h of PECS training (Phases I-III). Signi? cant increases were found for total child-toadult initiations, linguistic initiations, the percentage of adult response, the percentage of child response, and signi? cant decrease in adult-to-child interactions with no opportunity for child response. These differences were found in comparison to both a pre-intervention measure over time and to a non-intervention and non-equivalent control group.Examining a subset of this group, who used at least one word during observations, Carr and Felce (2007a) reported that over 6 weeks training in PECS phases I-III, 3 of the 24 children in the PECS group increased their spoken words. A further 2 who did not speak at pretesting did so at post-testing, while there was a marginal increase in speech for one child in the control group. RCTs Only three RCT studies were located. Yoder and Stone (2006a) conducted an experimental study of 36 children with autism, aged 21–54 months, who were randomly assigned to PECS or RPMT intervention groups. They found that the PECS group showed a signi? cantly greater increase in frequency of speech (d = 0. 3) and in number of different words used (d = 0. 50) after 6 months of intervention, but by 6 months post-intervention the difference was no longer evident. Interestingly, they also found differing effects according to pretreatment characteristics: children who were low in initial object exploration bene? ted more from the RPMT intervention, while those who were higher bene? ted more from PECS, these effects being evident 6 months post-intervention. Overall, there was a signi? cant increase in non-imitative spoken acts over 1 year. The actual increases were from a mean of 0. 25 nonimitative spoken acts in a 15-min session to a mean of 5. 5, and from a mean of 0. 7 different non-imitative words to a mean of 3. Given the young age of the children, the fact that their initial verbal mental age averaged 11. 9 months (range 7–19 months), just at the stage when verbal language is likely to develop naturally, it seems quite possible that this increase could be attributed to maturation. In a second article, Yoder and Stone (2006b) examined the effect of the interventions on the three major types of intentional communication used prior to speech development, (i. e. initiating joint attention, requesting, and turn-taking). They found that, overall all three comm unicative functions increased signi? cantly, but RPMT increased turn-taking more than PECS.Children who were higher in initiating joint attention before treatment had greater increases in both initiating joint attention and requesting following RPMT intervention, while those who were initially lower in initiating joint attention had greater increases following PECS intervention. Howlin et al. (2007) conducted a group RCT of 84 children with autism, examining the effect of teacher training and consultancy in PECS. It should be stressed that this study examined the effectiveness of a consultancy model to deliver PECS, rather than the ef? cacy of PECS per se. Thus, the study was noteworthy in that it appears to be the only research to examine effectiveness (i. e. , outcomes under clinical rather than optimal conditions). Howlin et al. ound that rates of communicative initiations and PECS usage were signi? cantly increased immediately following intervention, but that these effects were not maintained once the intervention ceased. They found no signi? cant increase in frequency of speech. Howlin et al. also examined ADOS-G (Lord et al. 2000) domain scores for communication and reciprocal social interaction. They found no increase in most ADOS-G ratings, with the exception of a decrease in the severity score for the Reciprocal Social Interaction domain at the 10 month followup. Unfortunately, no data was provided on the ? delity of implementation of the PECS program, or indeed on the ? delity of the teacher training.Maintenance and Generalization Only ? ve studies provided data on maintenance. Two of the RCT studies included long-term follow-up. Yoder and Stone (2006a) found that differences in speech variables were not maintained 6 months post-intervention, while Howlin et al. (2007) found that for the 26 children assessed at a 10-month follow-up, the increased rate of communicative initiations and PECS usage found immediately post-intervention was not maintained. Two single subject studies and one case study measured maintenance of skills 6–10 months postintervention (Charlop-Christy et al. 2002; Malandraki and Okalidou 2007; Yokoyama et al. 2006). Charlop-Christy et al. ound that speech and socio-communicative behaviors had been maintained or continued to increase for one participant followed up 10 months post-training. Yokoyama et al. found maintenance of PECS skills both in the training room and at home, 6–8 months after training for the three participants in their study. Malandraki and Okalidou in their study of one child found maintenance of skills 6 months after the main intervention. While the difference was not signi? cant and the number of studies was low, for the single 123 J Autism Dev Disord (2009) 39:1471–1486 1481 subject studies both PND and PEM were lower for studies that included maintenance data (Table 4).Fifteen of the 27 studies included some data on generalization of PECS skills. The great majority o f these were positive, with skills generalizing to different settings, people and stimuli. For some studies, generalization was an integral part of the way data were collected (CharlopChristy et al. 2002; Yoder and Stone 2006a, b). For others, generalization to untrained situations was speci? cally probed (e. g. , participants in Stoner et al. ’s (2006) study generalized their skills to use in fast food restaurants). Several studies demonstrated generalization to the classroom teacher or to home. In a small number of instances, generalization was unimpressive or absent.For example, in the Adkins and Axelrod (2001) study, tests for ‘‘generalization’’ simply required the child to mand for an object without immediately prior prompted trials. ‘‘Carl’’, from Tincani’s (2004) study, failed to generalize PECS skills to classroom teachers, preferring to use sign language. Discussion The PECS program was originally designed to provide a method of communication for children with autism, particularly those who do not use functional speech. PECS appears to be a popular intervention (Howlin et al. 2007) but, unfortunately, popularity of a given treatment does not necessarily re? ect actual ef? cacy (Green et al. 2006; Reynhout and Carter 2006). Only three RCTs have been reported to date. The studies of Yoder and Stone (2006a, b) compared PECS to RMPT.PECS was superior for some children but the study was designed to compare two treatments and, consequently, did not include a control arm. Thus, no conclusions can be drawn about the relative superiority of either intervention to a non-treatment control. Howlin et al. (2007) provided the only effectiveness study conducted. They found signi? cant effects on communicative initiations but this was not maintained once the intervention ceased. Thus, further examination of approaches to the delivery of PECS in clinical settings is needed. Con? dence in the Howlin et a l. study is somewhat weakened by the lack of any data on treatment ? delity, which is a critical feature in study quality (Gersten et al. 2005).The nature and quantity of data arising from RCTs at this point in time is insuf? cient to draw ? rm conclusions regarding the PECS interventions. Thus, probably the highest priority for research in this area is the conduct of further RCTs examining both ef? cacy and effectiveness in applied settings. In the absence of an adequate body of RCTs, clinicians still need to make informed decisions regarding interventions and may need to look to the second line of evidence. Evidence supporting the PECS intervention was provided by the well-designed quasi-experimental studies of Carr and Felce (2007a, b), which incorporated a non-equivalent control group with demonstration of pre-test equivalence between groups.Arguably, the bulk of interpretable data on PECS comes from single subject studies. For the relevant studies, the overall, mean PND (78. 5% ) and PEM (89. 1%) ? gures support the preliminary conclusion that PECS may be an effective intervention, at least when implemented under research conditions. There was a signi? cant difference between the PND results for studies that only looked at picture exchange outcome variables and those that included other collateral variables, such as speech, social, or challenging behavior. This indicates that, unsurprisingly, PECS training appears to be most effective in providing a successful means of communication through picture exchange.Nevertheless, it should be acknowledged that the number of studies remains relatively low and single subject designs have several limitations, including low external validity. While these studies contribute to our knowledge and give us a preliminary indication of the ef? cacy of PECS, they are not a substitute for well-conducted large scale RCTs. A substantial number of the extant studies were preexperimental in nature, particularly the early research. As such, they are not able to provide convincing demonstrations of experimental control. Hence, these studies offer no interpretable evidence on the ef? cacy of PECS. The effect of PECS training on speech development remains unclear.Research into various forms of AAC suggests they may have the potential to enhance speech development (Cress and Marvin 2003; Millar et al. 2006; Romski and Sevcik 2005) although results have sometimes been inconsistent (Carter 1999; Millar et al. 2006). Several of the studies reviewed in this paper reported increases in speech following PECS training, but others, including Howlin et al. (2007), reported little or no effect. Where speech increased, this has often occurred concurrently with phase III or IV of PECS, and in particular when a time delay was introduced. A related question, for which there is as yet no empirical evidence, is whether PECS training affects comprehension.Brady (2000) found increased comprehension skills with the use of VOCAs and it would be worth investigating whether PECS would have a similar effect. In comparison with other AAC systems, better overall results were obtained with PECS in the studies reviewed here (Adkins and Axelrod 2001; Bock et al. 2005; Chambers and Rehfeldt 2003; Tincani 2004). Nevertheless, there was variability in the results depending on initial imitation skills and, possibly, participant preference. It has been argued that individuals with ASD may bene? t from visually cued instruction (Quill 1997) and further examination of this issue would seem warranted. In addition, existing 123 1482 J Autism Dev Disord (2009) 39:1471–1486 application of PECS appears to have been exclusively limited to graphic symbols.There are distinct advantages to the use of three-dimensional tangible symbols, including decreased cognitive load and high iconicity (Rowland and Schweigert 1989, 1990; Turnell and Carter 1994). The exploration of the use of PECS with tangible symbols, especially with indiv iduals who are low functioning, would seem warranted. Only 5 of the 27 studies provided data on maintenance of PECS skills or other dependent variables. It is worthy of note that maintenance was problematic in both RCTs (Howlin et al. 2007; Yoder and Stone 2006a) that examined the issue. Overall, available evidence is mixed but there is certainly suf? cient doubt to indicate that maintenance should be formally and systematically monitored in the clinical application of PECS programs.Fifteen studies provided data on generalization of skills, the vast majority of these found that generalization did occur, but what was described as ‘‘generalization’’ varied greatly. There were several methodological limitations and issues in the research examined that warrant comment. In general, participant descriptions were poor, making it dif? cult to assess whether the intervention is best suited to individuals with particular characteristics. While nearly all studies prov ided a diagnosis, few speci? ed the diagnostic protocol or criteria. Further, when participants were diagnosed with ASD, few researches attempted to quantify the degree of autism.Noting the range of behaviors and symptom severity possible within individuals presenting with autistic disorder, and even greater variation in the broader autism spectrum, this would seem to be relevant, if not critical, information. Few researchers provided standardized assessment data or a detailed functional description of general ability, but probably re? ecting the aim of the intervention, most did provide some description of initial communication skills. While the number of studies was clearly insuf? cient to reach ? rm conclusions, PND data suggest that individuals with PDD-NOS or showing autistic traits made more progress with PECS than those with autistic disorder.It is unclear whether this is because the PECS protocol is better suited to them, or because they would do better with any treatment. W ithout further clear and consistent quanti? cation of the degree of autistic symptomatology, it is impossible to evaluate further this variable in relation to the ef? cacy of the PECS intervention. In addition, there was insuf? cient data on intellectual functioning to enable analysis of any relationship to PND or PEM. It is recommended that, in future studies, standardized psychometric data, standardized functional assessment of adaptive behavior, and clear information on initial communicative abilities should be provided.In addition, where a diagnosis of autism is provided the level of autistic symptomatology should be quanti? ed. Procedural reliability data were very limited, with data only meeting the conventional minimum standard in 5 of the 27 studies. Because of the absence of this data, it is not possible to determine in many cases whether what was being implemented was in fact the PECS program as designed. PECS is a complex and multi-component intervention making the veri? cation of treatment integrity even more critical. The absence of such information in research studies is somewhat dif? cult to understand given that the PECS manual (Frost and Bondy 2002) gives explicit and speci? criteria for assessing the integrity of training during each phase. Nevertheless, research on PECS is not alone in this regard and lack of procedural reliability data has been reported as a problem in other recent intervention reviews in the area of autism (e. g. , Bellini and Akullian 2007; Reynhout and Carter 2006). The calculated PND (88. 8%) and PEM (89. 9%) ? gures for studies that did meet the standard for reporting procedural reliability, are at the high end of the effective intervention range (Ma 2006; Scruggs and Mastropieri 1998), suggesting that monitoring of procedural integrity should be a key feature in research as well as clinical applications of PECS. A signi? ant component of the present review was the application of PND and PEM metrics to the relevant dat a. PND and PEM values were in most cases very similar, with lower variability for PEM (see Table 4). An exception was found for data relating to behavioral variables (CharlopChristy et al. 2002; Frea et al. 2001), where high baseline variability and ‘‘? oor’’ effects occurred, often causing the calculated PND for affected graphs to be low, while the PEM was high. For example, visual inspection of the graphed data in Frea et al. (2001) shows a clear treatment effect of the PECS intervention on disruptive behavior. Nevertheless, the calculated PND for these data was 0%, while the PEM was 100%.The discrepancy between the clear treatment effect seen in the graphed data and the PND value indicates that PEM may be a more appropriate metric for challenging behavior, where variability is likely to be high. Further, the advantages of using multiple methods of calculating effect sizes for single subject research are highlighted. As previously noted, PECS is a complex multi-component intervention program. Consequently, the question arises as to which of the components are most critical to its ef? cacy. For example, reinforcer assessment is formally and systematically incorporated into PECS and this may well be a salient factor in program ef? cacy. The use of picture exchange with a partner (rather than touching or pointing to a symbol) is a key distinguishing feature of PECS, but it is unclear whether exchange per se is essential to ef? cacy.The issue of developing spontaneity is addressed in an unusually systematic way in the PECS program (Chiang and Carter 2008) but extant research 123 J Autism Dev Disord (2009) 39:1471–1486 1483 provides only limited information on the circumstances under which communication occurs. Thus, there would appear to be considerable scope for examination of how speci? c components contribute to the overall ef? cacy of PECS. In addition, there has been only limited comparison of PECS to alternative interventio ns and this stands as a priority for future research. Several limitations of the current review must be acknowledged. Many of the earlier studies were descriptive and clear experimental control was not established.While later studies were of higher quality, only a limited number of RCTs have been conducted and much of the available interpretable data comes from second line of evidence single subject studies. Analysis of PND and PEM was only possible for a subset of the relevant single subject studies examined and analysis of speci? c study and participant characteristics were based on low numbers. In addition, very few studies provided adequate procedural reliability data so the extent to which PECS was appropriately implemented often remained unknown. Conclusion On balance, the studies reviewed provide preliminary evidence that PECS may be ef? cacious for children and adults with ASD and other developmental disabilities, who have little or no speech. Primary bene? s appear to be ev ident in communication by picture exchange. Identi? cation of the core aspects of the program that are important to its success, the individuals to whom it is best suited, and its relationship to other interventions remain to be substantively investigated. PECS stands as a promising intervention with some empirical support but many questions remain. The conduct of further RCTs into the ef? cacy and effectiveness of PECS stands as a high research priority. Appendix See Table 6. Table 6 Quality criteria for single subject research adapted from Horner et al. (2005) Area Indicator Description of participants Participants are described with suf? ient detail to allow others to select individuals with similar characteristics and settings (e. g. , age, gender, disability, diagnosis). One point awarded for each of the following (maximum of 5): 1. Statement of diagnosis such as autism, ASD, Asperger syndrome, intellectual disability (with or without indicating diagnostic source), age and gend er 2. Diagnostic instrument speci? ed (e. g. , WISC, AAMR diagnostic criteria, DSM-IV criteria, ADOS). Must provide if ASD or 0 awarded 3. If ASD, degree of autism speci? ed either with reference to symptoms (DSM-IV) or instrument like CARS. If not ASD, award point 4. Standardized assessment data (e. g. IQ, developmental scale, adaptive behavior) OR detailed functional description of general ability. Disability range (e. g. , moderate) acceptable for intellectual disability 5. Communication skills documented by means of standardized test results OR description of functional skills The process for selecting participants is described with replicable precision. MUST describe the process used to select participants, not just describe the participants or their needs. This would generally include the criteria the participants must meet (e. g. , 3–5 years, less than 5 spoken words, diagnosis of autistic disorder) and or the process of selecting participants (e. g. , the ? rst 5 chil dren on the waiting list).Essentially, authors must explicitly state HOW/WHY participants were selected Critical features of the physical setting are described with suf? cient precision to allow replication Dependent variables All dependent variables are described with operational precision Each dependent variable is measured with a procedure that generates a quanti? able index The measurement process is described with replicable precision Dependent variables are measured repeatedly over time Data are collected on the reliability or inter-observer agreement (IOA) associated with each dependent variable, and IOA levels meet minimal standards (i. e. , IOA = 80%; Kappa = 0. 60).Must be on minimum of 20% of sessions to be acceptable Independent variables Independent variable is described with replicable precision Independent variable is systematically manipulated and under the control of the experimenter Overt measurement of the ? delity of implementation for the independent variable. M UST be measured on a minimum of 20% of sessions to be acceptable 123 1484 Table 6 continued Area Baseline Indicator J Autism Dev Disord (2009) 39:1471–1486 A baseline phase provides repeated measurement of a dependent variable and establishes a pattern of responding that can be used to predict the pattern of future performance if introduction or manipulation of the independent variable did not occur. Should include a minimum of 3 stable data points.High variability is acceptable if intervention effects are unambiguous The procedural characteristics of the baseline conditions should be described operationally Experimental control/internal The design provides at least three demonstrations of experimental effect at different points in time. Effects of validity alternating treatments may be added, as main comparison is not with baseline. AB designs may not be added as they do not demonstrate intervention at different times when comparing to baseline The design controls for common threats to internal validity (e. g. , permits elimination of rival hypotheses). Acceptable designs include multiple baseline, ABAB and alternating treatment with counterbalancing.Unacceptable designs include: AB, ABA, and changing criterion External validity Social validity Experimental effects are replicated across participants, settings, or materials to establish external validity. At least three participants, settings or materials must be apparent The dependent variable is socially important Implementation of the independent variable is practical and cost effective (must be measured) Social validity is enhanced by implementation of the independent variable over extended time periods, by typical intervention agents, in typical ph