Many academic tests (e.g. short-answer and multiple-choice) sample required knowledge with questions scoring 0 or 1 (dichotomous scoring). Few textbooks give useful guidance on the length of test needed to do this reliably. Posey's binomial error model of 1932 provides the best starting point, but allows neither for heterogeneity of question…

Two psychometric models are presented for evaluating the difficulty of the distractors in multiple-choice items. They are based on the criterion of rising distractor selection ratios, which facilitates interpretation of the subject and item parameters. Statistical inferential tools are developed in a Bayesian framework: modal a posteriori…

Technical considerations associated with item selection and reliability assessment are considered in relation to criterion-referenced tests constructed to provide group information. The purpose is to emphasize test building and the evaluation of test scores in program evaluation studies. It is stressed that an evaluator employ a performance or…