As a result of the 1998 reauthorization of Head Start, the Department of Health and Human Services conducted a national evaluation of the Head Start program. The goal of Head Start is to improve the school readiness skills of low-income children in the United States. There is a substantial body of experimental and correlational research that has…

This "What Works Clearinghouse Procedures and Standards Handbook (Version 3.0)" provides a detailed description of the standards and procedures of the What Works Clearinghouse (WWC). The remaining chapters of this Handbook are organized to take the reader through the basic steps that the WWC uses to develop a review protocol, identify…

This paper introduces an empirical strategy to estimate dynamic treatment effects in randomized trials that provide treatment in multiple stages and in which various noncompliance problems arise such as attrition and selective transitions between treatment and control groups. Our approach is applied to the highly influential four year randomized…

Describes problems in implementing placebo controls in psychotherapy including the difficulty of ensuring that therapists and their patients will view both the experimental and placebo treatments as comparably credible. Considers six research issues stemming from the definitional requirement that the placebo control for the critical and specific…

The third-year evaluation of the federally funded Washington, D.C. voucher program shows that low-income students offered vouchers in the first two years of the program had modestly higher reading scores after three years but showed no significant difference in mathematics. Students were randomly assigned to treatment and control groups, and the…

An examination of the scientific basis of both control group designs and comparative designs in outcome research reveals that comparative designs generally have fewer threats to validity and provide a more efficient means of control for nonspecific treatment factors suggesting that comparative studies warrant a larger role in the study of…

This article discusses the difficulties in conducting intervention research or evaluating intervention programs in a school setting. In particular, the problems associated with randomization and obtaining control groups are examined. The use of quasi-experimental designs, specifically a paired comparison design using the individual as his or her…

Is it ethical to select clients at random for a beneficial social service, then deny the benefits to a control group for the sake of science? Participation of control groups in planning, implementation and evaluation of social programs may resolve ethical issues. (Author/CP)

Recognition of radio and television antismoking messages was measured in 6 treatment and 4 control cities. A survey of 574 adolescents found high recognition of messages even in areas where they were not broadcast, reinforcing the need for true control groups and distinctive messages to ensure validity in mass media evaluation. (SK)

This article discusses the use of propensity scoring in experimental program evaluations to estimate impacts for subgroups defined by program features and participants' program experiences. The authors discuss estimation issues and provide specification tests. They also discuss the use of an overlooked data collection design--obtaining predictions…

A persistent problem in the evaluation of field-based projects is the lack of no-treatment comparison groups. Frequently, potential comparison groups are confounded by socioeconomic, racial, or other factors. Among the possible methods for dealing with this problem are various matching procedures, but they are cumbersome to use with multiple…

Evaluations occur within a political decision-making mileau, where multiple stakeholders are contending for limited funds. Given the subjective basis of empirical information, different conclusions or recommendations about a program may result from different ideological, theoretical, and disciplinary perspectives. The logic behind the…

The subject mortality problems of an experimental design which covers the period of student recruitment through posttesting over a 13-month period, is detailed in this study. Out of an effective applicant pool of 72 students randomly assigned to experimental and control groups, only 38 students remained at the end of the study with complete test…

A solution to the problem of specification error due to excluded variables in statistical models of treatment effects in nonrandomized (nonequivalent) control group designs is presented. It involves longitudinal observation with at least two pretests. A maximum likelihood estimation program such as LISREL may provide reasonable estimates of…