A Didactic Presentation of Snijders's lz* Index of Person Fit With Emphasis on Response Model Selection and Ability Estimation KU Leuven
This paper focuses on two likelihood-based indices of person fit, the index lz and the Snijders's modified index l z*. The first one is commonly used in practical assessment of person fit, although its asymptotic standard normal distribution is not valid when true abilities are replaced by sample ability estimates. The l z* index is a generalization of l z, which corrects for this sampling variability. Surprisingly, it is not yet popular in the ...