THE NEW RULES OF MEASUREMENT

Classical test theory, which the authors maintain applied psychologist s are still too often exclusively taught, are contrasted with the new rules of measurement. In the newer, model-based version of test theory , called item response theory (IRT), some well-known rules of measurem ent no longer apply. Six old rules bf measurement that conflict with t he new rules are reviewed, and intuitive explanations of the new rules are provided. Readers are also directed to additional informational s ources about IRT, which, it is argued, every psychologist should be fa miliar with.