Formulas for the standard error of measurement of three measures of change (simple differences; residualized difference scores; and a measure introduced by Tucker, Damarin, and Messick) are derived. A practical guide for determining the relative error of the three measures is developed. (Author/JKS)

A new computing algorithm, MAPCLUS (Mathematical Programming Clustering), for fitting the Shephard-Arabie ADCLUS (Additive Clustering) model is presented. Details and benefits of the algorithm are discussed. (Author/JKS)

A statistical method for testing the agreement between a judge's assessment of an object or subject and a known standard is developed and shown to be superior to two other methods which appear in the literature. (Author/JKS)

An individual differences additive model is discussed which represents individual differences in additivity by differential weighting or additive factors. A procedure for estimating model parameters for various data measurement characteristics is developed. The method is found to be very useful in describing certain types of developmental change…

An extension to the partial credit model, the linear partial credit model, is considered under the assumption of a certain linear decomposition of the item x category parameters into basic parameters. A conditional maximum likelihood algorithm for estimating basic parameters is presented and illustrated with simulation and an empirical study. (SLD)