The Rasch model and other latent trait models encounter some difficulty when faced with an appreciable amount of missing data or omitting behavior. The present note assumes that some reasonable missing data model has been formulated which does not involve the parameters associated with the latent ability of interest. A maximum likelihood function…

The concepts of elevation, scatter, and shape are investigated as parameters in assessing the similarity among profiles of individuals. A computational strategy for differentiating the independent contribution of each parameter to more global indices of resemblance is presented. (Author/JKS)

Many models have been proposed for examining factors from several batteries of tests. A model for such an analysis is presented which allows for maintaining the distinction among batteries. A discussion of the computational procedures is given, and examples are provided. (Author/JKS)

This paper outlines a methodology that school districts can use to enhance the presentation of district-wide testing program results to administrators, school boards, teachers, and the public. Based on John Tukey's two way analysis methodology, it involves fitting this model: test score equals overall plus year plus grade plus cohort plus…

Classical test theory, item response theory, and generalizability theory all treat the abilities to be measured as continuous variables, and the items of a test as independent probes of underlying continua. These models are well-suited to measuring the broad, diffuse traits of traditional differential psychology, but not for measuring the outcomes…

The family of Weibull distributions was investigated as a model for the distributions of response times for items in computer-based criterion-referenced tests. The fit of these distributions were, with a few exceptions, good to excellent according to the Kolmogorov-Smirnov test. For a few relatively simple items, the two-parameter gamma…