The software offers tests for regression slope and intercept to analyze test bias. It is a useful tool for identifying any potential bias in test scores.
One of the early influential positions regarding the importance of predictive validity indicates that a test is considered fair for a particular use if the inference drawn from the test score is made with the smallest feasible random error, and if there is no constant error in the inference as a function of membership in a particular group.
MacPotthoff provides users with one of the most popular methods for detecting bias of prediction, published by R. F. Potthoff in 1978. Potthoff's model offers both simultaneous and separate tests of regression slopes and intercepts. If a significant F results from the simultaneous test, one may conclude that predictive bias exists and may then conduct separate tests of slopes and intercepts to ascertain whether the bias in prediction is constant (intercepts differ) or varies relative to the distance of scores from the mean (slopes differ).
It is generally accepted that no test bias exists if the predictive relationship of two or more groups can be adequately described by a common regression line. MacPotthoff users can also find an application of the Potthoff procedure in Weiss and Prifitera (1995) if they would like to see it in action.
Version 2.1: N/A