Introduces an new approach for measuring the impact of whole school reforms. The approach, based on "short" interrupted time-series analysis, is explained, its statistical procedures are outlined, and how it was used in the evaluation of a major whole-school reform, Accelerated Schools is described (H. Bloom and others, 2001). (SLD)

A simple way to assess the statistical power of experimental designs, based on the concept of a minimum detectable effect, is described. How to compute minimum detectable effects and how to apply the method of assessment of alternative experimental designs are illustrated. (SLD)

Explores the possibility of randomly assigning groups (or clusters) of individuals to a program or control group to estimate the impact of programs designed to affect whole groups. Applies the cluster-assignment approach to the evaluation of education programs targeting whole schools. Discusses statistical implications of the method. (SLD)