A Consumer's Guide to LOGIST and BILOG

Abstract

Since its release in 1976, Wingersky, Barton, and Lord's (1982) LOGIST has been the most widely used computer program for estimating the parameters of the three-parameter logistic item response model. An al ternative program, Mislevy and Bock's (1983) BILOG, has recently become available. This paper compares the approaches taken by the two programs and offers some guidelines for choosing between the two pro grams for particular applications. Index terms: Bayesian estimation, BILOG, IRT estimation procedures, LOGIST, marginal maximum likelihood, maximum like lihood, three-parameter logistic model estimation pro cedures.