A KERNEL-SMOOTHED VERSION OF SIBTEST WITH APPLICATIONS TO LOCAL DIF INFERENCE AND FUNCTION ESTIMATION

Smoothed SIBTEST: a nonparametric DIF detection procedure, amalgamates SIBTEST and kernel-smoothed item response function estimation. This p rocedure assesses DIF as a function of the latent trait theta that the test is designed to measure. Smoothed SIBTEST estimates this function with increased efficiency, as compared to SIBTEST: while providing hy pothesis tests of focal and global DIE By means of kernel smoothing, s moothed SIBTEST reduces noise in local DIF estimation while retaining SIBTEST's reduction of group-ability-difference-induced DIF estimation bias via use of regression-corrected estimates of ability as design p oints in the kernel smoothing. By contrast with most nonparametric pro cedures, matched examinee score cells are not needed, so sparse cell p roblems are avoided The performance of smoothed SIBTEST is studied via simulation and real data analysis.