The studies in this special section of the "Journal of Educational Psychology" present a variety of social-psychological interventions across large numbers of classrooms and populations. They show notable benefits for many students at risk for low performance. This is the glass half-full interpretation, and we consider the strengths of…

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…

This article examines the effectiveness of incentives in improving survey response rates of school counselors and compares the findings with those of previously researched populations. A $1 cash incentive increased response rates for a one-wave mailing of a questionnaire, while a raffle opportunity did not. The number and length of optional…

The use of analysis of variance was examined under the assumption that the treatment had been randomly assigned to students, when in fact, the class had been the unit. Data support the idea that if one can randomly assign treatments to intact classes, consideration should certainly be given to doing so. (Author/GK)

This paper reviews limitations in the interpretations of group differences in studies that use younger, language-matched controls in addition to age-matched controls to examine the role of "language level" on performance. Problems arise because of the multidimensional nature of language, extraneous age effects associated with language matching,…

The need to attend to both methodological and social concerns is demonstrated in two examples: one where the unchecked effects of the social consequences of a methodologically rigorous research design invalidated the evaluation and a second where explicit trade-offs between methodological rigor and social costs enabled the evaluation to proceed.…

Reviews research into class size effects from a methodological viewpoint, concentrating on various strengths and weaknesses of randomized controlled trials (RCT) and observational studies. Discusses population definitions, causation, and generally sets out criteria for valid inferences from such studies. Illustrates with new findings from data in…

Examines the Type I Error in research on multimedia's impact on learning. Discusses the lack of a control group; the myth of multimedia benefits and the motivational effects of curiosity, content, and instructional strategies; the economics of multimedia; and dangers of the Type I Error, including inequity, lower scores or standards, wasted…

Evidence is presented that strengthens the argument against comparison group research strategies. Results from a study of youth attitudes related to the California Conservation Corps involving 528 participants and 668 comparisons indicate that the comparison group may not adequately represent the nontreatment state. (SLD)

An evaluation of an experimental problem-based medical education curriculum used with 18 first-year students at the Bowman Gray Medical School of Wake Forest University is discussed. The study, which included a matched group of students experiencing a traditional curriculum, provides insights into design problems in such evaluations. (TJH)

Problems with conducting randomized field experiments in education are explored. Focus is on problems encountered while evaluating a group of dropout prevention projects. Project planners were asked to manipulate the subject eligibility criteria until they identified as eligible three to four times as many students as they could serve. They were…

The focus of future Follow Through research should be oriented toward showing what can be done in order to offer information to both federal and local planners on which systems of curriculum design, classroom management, and parent involvement appear to be most effective. To assure this goal, the issues of program efficacy and implementation…