The pretest-posttest design referred to as Design 2 by Campbell and Stanley (1963) is commonly used in educational research and evaluation. The tenability of the assumption of a zero population difference commonly used with this design is questioned. A nonzero population estimate based on the mean difference observed in test-retest reliability…

The evaluation design, which prescribes when and from whom to gather data, is described as significant because it can lend credibility to evaluation results. The objectives of this booklet are to aid the evaluator in: choosing a design; putting it into operation; and analyzing and reporting the data. Examples include both formative and summative…