MacPotthoff: automated calculation of the Potthoff regression bias procedure.

Test bias, in contrast to test fairness, is best conceptualized in validity terms amenable to statistical analysis. Evidence of predictive validity may be most salient in many situations. Evaluation of predictive bias is generally operationalized via linear regression. Potthoff (1978) provided an efficient and parsimonious regression bias procedure that allows both simultaneous and separate tests of regression slopes and intercepts across groups. A Macintosh computer program, MacPotthoff, is presented for automated calculation of Potthoff regression bias statistics.