An interactive computer program for tailored testing based on the one-parameter logistic model

A program to implement tailored testing using the Rasch one-parameter logistic model is described and the problems encountered in its writing are discussed.     

An interactive multiobjective programming approach to combinatorial data analysis

Combinatorial optimization problems in the social and behavioral sciences are frequently associated with a variety of alternative objective criteria. Multiobjective programming is an operations research methodology that enables the quantitative analyst to investigate tradeoffs among relevant objective criteria. In this paper, we describe an interactive procedure for multiobjective asymmetric unidimensional seriation problems. This procedure uses a dynamic-programming algorithm to partially generate the efficient set of sequences for small to medium-sized problems, and a multioperation heuristic to estimate the efficient set for larger problems. The interactive multiobjective procedure is applied to an empirical data set from the psychometric literature. We conclude with a discussion of other potential areas of application in combinatorial data analysis.Stephanie Stahl is a freelance writer and editor. She can be reached via e-mail at s-stahl@worldnet.att.net.     

PERMAP: An interactive program for making perceptual maps

This article describes a DOS-based computer program for making and testing perceptual maps. The program, PERMAP, uses conventional metric multidimensional scaling techniques. That is, it uses pairwise numerical values (correlations, proximities, dissimilarities, etc.) to construct a map showing the relationship between objects. A unique feature of PERMAP is that it embeds the mapping techniques in an interactive, graphical system that minimizes several difficulties associated with multidimensional scaling practices. It is particularly effective at exposing artifacts due to local minima, incomplete convergence, and the effects of outliers. It can associate various attributes with the resultant groupings and provide line-linking options to help the researcher identify the nature of perceived relationships. Problems involving multiple matrices can be treated using three different aggregation methods. The optional use of weighting factors is available.     

A computer program for determining optimal data transformations minimizing skew

A program is presented that solves for an optimal transformation of data that minimizes skew. Various possible transformations are represented by a function that depends upon a single parameter, λ. A process of iterative approximations is employed to find a value of λ that will transform the data so as to produce a third moment equal to zero. The transformation found by this process may be used as computed or used to indicate which of the commonly employed transformations will most adequately counteract skew. The use of this program in processing data before analysis of variance is discussed.