A Monte Carlo Examination of External Unfolding

Abstract

Monte carlo techniques were used to examine regression approaches to external unfolding. The pres ent analysis examined the technique to determine if various characteristics of the points are recovered (such as ideal points). Characteristics of the situations were manipulated, including number of stimuli, error level, and measurement level. Generally, monotonic analyses resulted in good recovery. Recovery was poor when the data were generated by a weighted Eu clidean process. Negative weights were commonly en countered, apparently due to error in the data. In this approach, estimation is done by statistical techniques, and some statistical concerns should be taken into ac count when examining the results. Index terms: ex ternal unfolding, monte carlo simulation, multidimen sional scaling, nonmetric methods, parameter estimation, unfolding.