This article presents a non-mathematical introduction to latent trait test models and some of their features. Latent trait models are compared to classical test models. Two promising applications of latent trait models and available computer programs are discussed. (Author/JKS)

This article explains the Rasch model for sample-free item analysis and test-free person measurement. It shows how to estimate model parameters from data and how to evaluate the statistical fit of these estimates to the data. Attention is paid to practical considerations. (Author/JKS)

A variety of practical applications of item characteristic curve test theory are discussed. Among these applications are tailored testing, two stage testing, determining whether two tests measure the same latent trait, and measuring item bias towards minority or other groups. (Author/JKS)