Blackwell Reference Online

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In psychology, psychometric tests are standardized data collection methods. To provide significant and interpretable results in an empirical study, a test must meet specific requirements that are laid down by test theory. Only if these preconditions are given can reliable and valid conclusions be drawn with respect to the “real” value of a person's trait or state under measurement. For standardized tests the raw score obtained during administration is transformed into a test score (e.g., an IQ or an anxiety score), which represents the intensity or strength of the trait/state to be measured on the level of an interval scale (→  Scales ). Classical test theory is influenced by →  measurement theory in physics. It is based on the assumption that every test value obtained consists of a “true” value (i.e., the “real” intensity of the person's trait or state) as well as an additional error value. The error part of measured values should be minimized or at least known in size. For that, classic test theory is based on the assumption that error values are balanced out during repeated testing, that the error value is independent of the strength or intensity of the personal state or trait (the “real” value), and that for separate test administrations error values are independent of each other. The goodness of a test is indicated by three different criteria. A test is objective if different ... log in or subscribe to read full text