Evaluators are often called upon to assess the effects of programs. To assess a program effect, evaluators need a clear understanding of how a program effect is defined. Arguably, the most widely used definition of a program effect is the counterfactual one. According to the counterfactual definition, a program effect is the difference between…

A randomized experiment that measures the impact of a social policy in a sample of the population reveals whether the policy will work on average with universal application. An experiment that includes only the subset of the population that volunteers for the intervention generates narrower "proof-of-concept" evidence of whether the…

This paper reviews the use of multiple trials, defined as multiple sites or multiple arms in a single evaluation and replications, in evaluating social programs. After defining key terms, the paper discusses the rationales for conducting multiple trials, which include increasing sample size to increase statistical power; identifying the most…

We examined the extent to which mathematics program evaluations that have been conducted according to methodologically rigorous standards have attended to the theories underlying the programs being evaluated. Our analysis focused on the 37 reports of K-12 mathematics program evaluations in the last two decades that have met standards for inclusion…

Traditionally, evaluation has primarily tried to answer the question "Does a program, service, or policy work?" Recently, more attention is given to questions about variation in program effects and the mechanisms through which program effects occur. Addressing these kinds of questions requires moving beyond assessing average program…

To answer "what works?" questions about policy interventions based on an experimental design, Peck (2003) proposes to use baseline characteristics to symmetrically divide treatment and control group members into subgroups defined by endogenously determined postrandom assignment events. Symmetric prediction of these subgroups in both…

This article presents discussion and recommendations on approaches to retrospectively evaluating development interventions in the long term through a systems lens. It is based on experiences from the implementation of an 18-month study to investigate the impact of development interventions on economic and social change over a 40-year period in the…

In the current climate of increasing fiscal and clinical accountability, information is required about overall program effectiveness using clinical data. These requests present a challenge for programs utilizing single-subject data due to the use of highly individualized behavior plans and behavioral monitoring. Subsequently, the diversity of the…

This study explores the use of citation analysis methods to assess the influence of program evaluations conducted within the area of science, technology, engineering, and mathematics (STEM) education. Citation analysis is widely used within scientific research communities to measure the relative influence of scientific research enterprises and/or…

The growth in the availability of longitudinal data--data collected over time on the same individuals--as part of program evaluations has opened up exciting possibilities for evaluators to ask more nuanced questions about how individuals' outcomes change over time. However, in order to leverage longitudinal data to glean these important insights,…

Considerable research has been conducted on the use of the findings of program evaluation, but little, if any, attention has been paid to the soundness of the methods of this research. If the methods are not sound or not well described in the research, the strength of the conclusions of the research is unknown. The authors examine the empirical…

Fidelity may be defined as the extent to which delivery of an intervention adheres to the protocol or program model originally developed. Fidelity measurement has increasing significance for evaluation, treatment effectiveness research, and service administration. Yet few published studies using fidelity criteria provide details on the…