中文摘要：

项目反应理论（IRT）是教育测量中的重要模型．在被试的项目反应存在缺失的情况下，曾莉等给出了0、1评分的IRT模型参数估计的2种MCMC算法．本文将这2种算法推广到等级反应模型（GRM），并将估计结果与传统的Multilog软件（将缺失统一替换为O）的估计结果进行比较．通过模拟研究，比较了在不同缺失机制、不同参数先验分布、不同被试人数和不同缺失比例下2种MCMC参数估计的结果，为实际应用中GRM的参数估计方法的选择提供参考．

英文摘要：

Item Response Theory （IRT） plays an important role in educational measurement. How to estimate item parameters with missing data in IRT is an interesting issue. Zeng Li et al. （2009） proposed two MCMC-methods to solve the problem for 2PL model. This article extends their methods to Graded Response Model （GRM）, a polytomous IRT in tests. In simulation study, the results of item parameter estimates of two MCMC-methods were compared with that of Multilog （missing responses are seemed as wrong responses）, a widely used software for parameter estimation. The comparison was made individually under different conditions： three types of missing mechanism, two kinds of parameter priors, two sample sizes and three missing data proportions. The study provides a reference for item parameters estimation of GRM in practical analysis.