An investigation of the sampling distributions of equating coefficients

Abstract

Using the characteristic curve method for dichotomously scored test items, the sampling distributions of equating coefficients were examined. Simulated data for broad-range and screening tests were analyzed using three equating contexts and three anchor-item configurations in horizontal and vertical equating situations. The results indicated that the sampling distributions were bell-shaped and their standard deviations were uniformly small. There were few differences in the forms of the distributions of the obtained equating coefficients as a function of the anchor-item configurations or type of test. For the equating contexts studied, the sampling distributions of the equating coefficients appear to have acceptable characteristics, suggesting confidence in the values obtained by the characteristic curve method. Index terms: anchor items, characteristic curve method, common metric, equating coefficients, sampling distributions, test equating.