Some Posterior Standard Deviations of the Graded Response Model

Seock-Ho Kim

DOI: 10.64028/uiyf369607

Keywords: Bayes modal estimation, graded response model, item response theory, posterior standard deviations

TL;DR: IRT Parameter Estimation

Abstract:

The procedures required to obtain the approximate posterior standard deviations of the parameters of the graded response model for polytomously scored items from Bayes modal estimation are described and used to generate values for some common situations.
The results were compared with those obtained from maximum likelihood estimation. It is shown that the use of priors may reduce the instability of Bayes modal estimates of the item parameters assuming the choice of priors is reasonable. The sample size required for acceptable accuracy for purposes of practical applications of item response theory may be inferred from the tables or the computer code in R. It is suggested that careful selection and specifications of priors be exercised to obtain the required precision when the graded response model is used in these situations.

Submission Number: 5