Research over the past 15 years concerning parametric and nonparametric statistics and 10 recently developed nonparametric techniques for testing interactions in experimental design are reviewed. The new nonparametric techniques are robust, powerful, versatile, and easy to compute. A fabricated dataset is used to illustrate the technique. (TJH)

Differential item functioning (DIF) is an important consideration in assessing the validity of test scores (Camilli & Shepard, 1994). A variety of statistical procedures have been developed to assess DIF in tests of dichotomous (Hills, 1989; Millsap & Everson, 1993) and polytomous (Penfield & Lam, 2000; Potenza & Dorans, 1995) items. Some of these…