But if a tester gives incorrect answers to certain questions, different questions relating to the same topics may pop up again. Classical Test Theory Classical test theory is based upon the True Score Model introduced by Spearman. It is hypothesized that an observed score is composed of a true score and an error score . Scaling, Equating Scaling is a study of developing systematic rules and meaningful units of measurement for quantifying psychological constructs and empirical observations. A typical example is to assign IQ to measure intelligence.
Equating is a study of establishing equivalent scores of two tests.
These mental constructs are commonly used in evaluation of treatment effectiveness. In a test, subgroups of testers often have very different distributions of proficiencies. It is a study of statistical procedures to examine systematic errors of standard tests. When certain categories of testers such as females and ethnic minorities receive lower than average scores due to systematic errors of a test, this test are considered biased and violates construct validity . Bayesian approach views scientific reasoning in probabilistic terms.