Linear and repeated measures models for the person parameters

Measurement Instruments based on the Rasch model are often used to estimate the location θ of a person on a latent trait. This may be done once, or at several time points, or under several conditions. It is not unusual that researchers want to investigate hypotheses with respect to latent ability: Is the average arithmetic ability higher for men or for women? Can the attitude towards foreigners be predicted by age and socio-economic status? And, as a repeated measures example, does fear decrease after behavior therapy? The present chapter presents linear and repeated measures models for the person parameter, that can be used to investigate these kind of hypotheses.