摘要:The objective of this study was to investigate estimation and concordance method’s accuracy parameter based on item response theory. Estimation method used were Joint Maximum Likelihood, Bayesian and Bayesian Modal; and concordance method used were mean and sigma method, and robust mean and sigma method with sample size of 500 and 800. Data source used was test of tryout of Senior High School year 2012. Hypothesis testing on comparative values of root mean square difference (RMSD) using one way anova and t test. The results were parameter estimation method of Joint Maximum Likelihood, Bayesian and Bayes Modal on two logistic model parameters that produced similar estimation result using sample size more than 500, robust mean and sigma method was more accurate than mean and sigma method.