The fit of an item response model is typically conceptualized as whether a given model could have generated the data. We advocate for an alternative view of fit, "predictive fit", based on the model's ability to predict new data. We derive two predictive fit metrics for item response models that assess how well an estimated item response…

Classification procedures are common and useful in behavioral, educational, social, and managerial research. Supervised classification techniques such as discriminant function analysis assume training data are perfectly classified when estimating parameters or classifying. In contrast, unsupervised classification techniques such as finite mixture…

Accomplished throwers conserve angular momentum when distal joints of the throwing arm reach peak velocity at a later time than their proximal neighbors. The result is an increase in velocity of the most distal segment--the hand. Past research indicates that skill level varies by the number of joints experiencing distal timing lag (time to peak…

Rough set theory (RST) is an emerging technique used to deal with problems in data mining and knowledge acquisition. However, the RST approach has not been widely explored in the field of academic achievement. This investigation developed an improved RST (IMRST) model, which employs linear discriminant analysis to determine a reduct of RST, and…

The value systems by which the users of purchased information services select which one to use or buy are found to differ sharply among different user populations, but the variable found to control them is a function of use, not of the user as an individual. Selection variables are summarized in a matrix of user values and interaction effects. The…

An overview of the evaluation issues associated with contraceptive social marketing programs is provided. Methodologies covered include survey techniques, cost-effectiveness analyses, retail audits of sales data, time series analysis, nested logit analysis, and discriminant analysis. (TJH)