Many evaluation students are still being taught the use of tests of statistical significance without being warned about their limitations. This paper discusses other estimates of treatment effects necessary to interpret between-group differences correctly. Sources to improve evaluation practice are also suggested. (SLD)

Evaluations of special education interventions are different from research on medical interventions. Educational evaluations would be more useful if they applied an actuarial, or probability approach. Information should be collected over time and using various measures, thus increasing the available data. (GDC)