Systematic Measurement Error

Abstract

Systematic errors bias measurements. Obviously, cheating is a biasing factor. Answer copying is a type of cheating, which can be detected by answer-copying indices. Satisficing is responding to items with less than optimal efforts. It is detectable by building instructional manipulation checks or bogus items into the test. A response style is a typical way of taking a test. Plodding is a style where test takers start slowly and take much time to answer items. It is counteracted by informing test takers on the amount of time and number of items that remain. Fumbling is a style where test takers start rather panicky. It cannot be prevented, but testing should be less panic arousing as possible. The extremity and midpoint styles are the tendencies to choose extreme and midpoint answer categories, respectively. Acquiescence and dissentience are tendencies of yea- and nay-saying, respectively, and are detectable if the test is balanced (i.e., has about equal numbers of indicative and contra-indicative items). Satisficing and fumbling yield aberrant response patterns and acquiescence and dissentience aberrant response patterns at balanced tests that are detectable by person-fit indices. Item nonresponse is the tendency to skip items. It is reduced by computerized test administration and re-approaching test takers who omitted items. These styles and tendencies are sometimes person characteristics that are of interest of their own. Deleting test takers who show styles or tendencies yields missing data that have to be handled in the analysis of the data (see Chap. 16).