Quasi-experiments are common in studies that estimate the effect of instructional interventions on student performance outcomes. In this type of research, the nature of the experimental design, the choice in assessment, the selection of comparison groups, and the statistical methods used to analyze the comparison data dictate the validity of…

This review focuses on what the author terms a reconsideration of the working credentials of the randomly controlled trial (RCT) design, and includes a discussion of popularly accepted aspects as well as some new perspectives. The author concludes that there is nothing either Imperative or superior about the need for RCT designs, and that an…

Cross-lagged methodology (CLM), which is virtually ignored by psychological researchers, is suggested for studies of causal relations in which controlled experimentation is unfeasible. The longitudinal facet in the design of CLM is highlighted. Advantages and limitations of the CLM are described. (SLD)

D. B. Rubin's model for causal inference in experiments and observational studies is enlarged to analyze the problem of "causes causing causes" and is compared to path analysis and recursive structural equations models. A special quasiexperimental design, the encouragement design, is used to give concreteness to the discussion by…