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Research conducted to establish a causal relationship between an intervention and impact on behavior. It is often conducted in controlled laboratory settings to assure the results are a function of the intervention rather than so other variable. The primary value of efficacy research is to identify promising interventions.

Executive Summary

What works?

Efficacy research is usually conducted in highly controlled settings so that a clear causal relation between an intervention and a behavior can be demonstrated. By conducting the research in laboratory settings there are usually constraints on how participants are selected; who implements the intervention, and the level of supervision over the implementation.

As a result of constraining participants, change agents, and by closely supervising the implementation, practitioners often see the research as being irrelevant, impractical, and impossible because they must serve all students without constraint; interventions are often implemented by individuals who have not been trained in the specific intervention; and the resources associated with the research are not available in most practice settings.

Efficacy research is the most common type of published research for reasons related to the promotion and tenure system in universities.

There are two primary functions of efficacy research. The first is that it identifies promising interventions that can be evaluated further. The second value is to identify basic mechanisms that account for an interventions impact.

Overview Back to Top

The objective of

efficacy research

is to demonstrate that an intervention impacts behavior, either academic or social. The primary concern is the demonstration of a causal relation between the intervention and the behavior. The research is often conducted in highly structured and controlled laboratory situations to clearly demonstrate impact and causation. This assures that the changes in behavior are the result of the intervention and not some other source of influence. Confidence in the relationship between the intervention and behavior increases as more of the extraneous variables are controlled. In efficacy research, the researcher works to reduce or eliminate uncontrolled variables so that there are no valid alternative explanations for the results.

Characteristics of Efficacy Research Back to Top

The usual means for accomplishing this level of precision is to carefully select the participants in the research, use highly trained change agents (often graduate students and research assistants), and provide close supervision to assure that the intervention is implemented with integrity.


The characteristics of the participants are well defined so that other subject variables do not influence the results of the research. For example, in practice settings, students in special education often have other conditions that can potentially impact the outcomes of research. Students with learning disabilities may also be labeled as depressed so it is difficult to evaluate the impact of an intervention if the student has two presenting issues. If an intervention is designed to impact some aspect of the learning disability then depression has to be selected out so that it does not make the results more ambiguous.

Efficacy research often has a relatively small number of participants. Because the objective of efficacy research is finding a causal link between an intervention and impact on behavior it does not make a great deal of sense to spend scarce resources on interventions that have not yet demonstrated their impact.

Change agents

Highly trained change agents are used in efficacy research. They assure that the intervention is implemented as designed so the results can be attributed to the intervention as it was designed and not some unspecified modification. The usual candidates for change agents at this level of research are graduate students and research assistants.


In addition to having highly qualified change agents, there is usually very close supervision of the change agents to assure that the intervention is implemented as designed. Any unsystematic changes in the intervention make it difficult to interpret the results and make claims about the role of the intervention.

Limitations of Efficacy Research Back to Top

One of the major limitations of efficacy research is that it is often difficult to directly translate the research to practice settings. Practitioners often see efficacy research as being irrelevant, impractical, and impossible.


Practitioners may see the research as irrelevant because it is done in settings that are very different than “real world” settings, and the participants are very different than the students of concern in these “real world” settings.


Efficacy research is often viewed as impractical because of the level of training required to implement the intervention. Teachers working in public school settings may not receive the necessary training to implement these interventions. As with many professions, teacher training often reflects the biases of the faculty of the training institution. Skills valued by the training institution may be very different than the skills required for a specific intervention. Instructional assistants, who have minimal formal training, carry out much of the work with students in special education. Finally, efficacy research is considered impractical because the resources necessary to supervise proper implementation are not available.


Many practitioners consider efficacy research to be impossible because the necessary resources -- fiscal, curriculum, and staffing resources -- are not available and are not likely to become available for an intervention validated under laboratory conditions that are very different from the realities of special- education, school-based programs.

The Status of Efficacy Research Back to Top

Efficacy research is the most common type of research published in professional journals. The question becomes why is there so much efficacy research if the larger educational community does not value it? The answer to this question lies in who does research in this country (US) and how that research is funded.

Faculty members at universities and colleges, who are under pressure to achieve tenure, primarily conduct research. The primary mechanism for achieving tenure is a record of high productivity that is largely measured by publication rates. It is easier to accomplish high publication rates if each individual study is relatively short. Typically, efficacy research requires less time and less effort than larger scale effectiveness research.

A second reason that efficacy research is more common is that, often, graduate students are doing the research to complete degree requirements. As a consequence, the studies are relatively brief so the students can advance through their training programs.

A third reason that efficacy research is so common is that much of the research is funded by government grants. These grants typically have three-year funding cycles. With such short cycles it is much easier to complete efficacy research than effectiveness research, which often requires much longer time frames to complete.

Value of Efficacy Research Back to Top

Efficacy research plays a very important role in the development of effective interventions. One of the primary functions of efficacy research is to identify practices that are promising. This can best be accomplished by conducting the research under highly controlled conditions so that the impact of the intervention can be evaluated easily. In less structured settings, the impact of the intervention may be constrained by factors that are unrelated to the intervention. If the intervention is evaluated in less controlled settings then promising interventions might be dismissed because of the effects of these extraneous variables.

A second value of efficacy research is that it allows the researcher to study the mechanisms that account for an intervention’s impact. For example, a researcher may, in the development of an instructional program, systematically vary the amount of feedback that a student receives about performance. The researcher can then evaluate the impact of feedback on the instructional task. The differences in performance related to teacher feedback can be attributed to reinforcement effects and an appropriate level of reinforcement for maximum impact can be determined. By understanding the basic mechanisms that are operating within an intervention, it can be modified in particular ways to meet the requirements of a specific circumstance without compromising its effectiveness.

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