Parameter Model

The focus of this study is the estimation procedures implemented in BILOG, a computer program. One purpose is to compare the item parameter estimates produced by various procedures available in BILOG. Four different models are used: the one, two, and three parameter model and a three parameter model with common guessing parameters. The results generally indicate that the various item parameter estimation procedures tend to yield:miler results. The major exception concerned the Bayesian and maximum likelihood procedures (MLP) applied to the three parameter model. The MLP has a tendency to produce more extreme estimates:flan the Bayesian procedure. A second purpose is to compare the ability estimates produced by the available procedures: maximum likelihood, expected a'posteriori, and maximum a'posteriori. The results indicated that: 11) robustification is not a strong effect on th