Item bias in a multiple-choice test can be detected by appropriate analyses of the persons x items scoring matrix. This permits comparison of groups of examinees tested with the same instrument. The test may be biased if it is not measuring the same thing in comparable groups, if groups are responding to different aspects of the test items, or if…

Experiments that assign intact groups to treatment conditions are increasingly common in social research. In educational research, the groups assigned are often schools. The design of group-randomized experiments requires knowledge of the intraclass correlation structure to compute statistical power and sample sizes required to achieve adequate…