Modeling the process by which participants are selected into groups, rather than adjusting for preexisting group differences, provides the basis for several new approaches to the analysis of data from nonrandomized studies. Econometric approaches, the propensity scores approach, and the relative assignment variable approach to the modeling of…

The methods used by Humphreys and Dachler to estimate effects in their analysis of Project TALENT data to test Jensen's Theory of Intelligence are shown to produce biased estimates. (Author/TA)

The study, a seventh in a series of longitudinal studies, was an investigation of causal and other relationships among leadership, climate, teacher, and student variables in curriculum engineering. Quantitative measures included principals' leadership, organizational climate, teachers' attitudes, teachers' performance, and students' achievement.…