GENDER-RELATED IMPACT AND DIFFERENTIAL ITEM FUNCTIONING IN A TEST OF NUMERICAL ABILITY

Gender-related impact and differential item functioning in a test of n umerical ability. Standardized tests reflect differences between group s, and we should distinguish whether they are real or a product of the measuring instrument itself. In the last few decades psychometric res earch has approached this problem with the growing development of the studies of the differential item functioning for subjects or groups wi th the same degree of ability. This study examines the possible existe nce of real differences (impact) according to gender in a test of nume rical ability and the possible differential item functioning (DIF), wi th two different procedures. The first is based on item response theor y and the second on confirmatory factor analysis. Results suggest a ca reful review of the content of several items of the test. An examinati on of the convergence of results obtained with the different procedure s supports the use of iterative purification mechanisms when working w ith confirmatory factor analytic techniques and the use of multiple co nvergent evidences in taking decisions in empirical studies.