Presents a speculative model for predicting differential rates of therapeutic change. From a review of 52 comparative psychotherapy studies, certain hypothesized relationships between the characteristics constituting the model and a variety of psychological treatment procedures were assessed. Use of the model for generating and guiding research is…

Sees need for research examining differences among psychotherapy treatments to use model to narrow search for variables mediating between treatment type and outcome. Asserts that tests of treatment selection models that cut across narrow theoretical differences among psychotherapies and that operationalize definitions of patient types hold promise…

Evaluations involving nonrandom assignment to treatment or control groups are vulnerable to an accidental or intentional confounding of a selection effect with the treatment effect. Two techniques, discriminant analysis and base expectancy analysis, permit separate estimation of the selection and treatment effects in the final results. (Author/CTM)

School context constrains and supports field researchers' data collection activities, just as it can influence the educational change processes being studied. For outsiders, the accessibility of a school is affected by a number of factors. These influence findings and have implications for achieving data comparability across several sites.…