ABSTRACT
Earlier chapters dealt with estimation of item and ability parameters for a single group of examinees. In many practical situations, it is necessary to analyze item response data obtained from two or more (Le., multiple) groups of examinees. The focus of the present chapter is on the method of obtaining item parameter estimates and the estimates of latent group characteristics for such multiple group data. In this context, the ability parameters for each examinee in a group are not to be estimated.
