Research Article

A Gibbs Sampler for the Multidimensional Item Response Model

Table 1

Posterior estimates and Gelman-Rubin 𝑅 statistics for 𝛼 1 , 𝛼 2 , 𝛽 , and 𝜌 1 2 when the specified intertrait correlation is 0.2 (chain length = 10,000, burn-in = 5,000).

TrueUniform priorsNormal priorsTrueUniform priorsNormal priors
Estimate ( 𝑅 )Estimate ( 𝑅 )Estimate ( 𝑅 )Estimate ( 𝑅 )

𝛼 1       𝛽
0.9050.962 (1.036)0.947 (1.223)βˆ’1.433βˆ’1.593 (1.017)βˆ’1.553 (1.219)
0.3100.229 (1.044)0.237 (1.007)βˆ’1.552βˆ’1.610 (1.027)βˆ’1.606 (1.010)
0.6050.579 (1.068)0.581 (1.007)βˆ’0.656βˆ’0.627 (1.005)βˆ’0.626 (1.014)
0.1170.082 (1.034)0.091 (1.015)βˆ’0.146βˆ’0.099 (1.011)βˆ’0.099 (1.010)
0.1970.064 (1.008)0.062 (1.003)βˆ’1.206βˆ’1.176 (0.999)βˆ’1.169 (1.001)
0.4980.517 (1.032)0.518 (1.012)βˆ’1.457βˆ’1.728 (1.100)βˆ’1.622 (1.021)
0.4420.443 (1.043)0.467 (1.085)1.9041.892 (1.025)1.831 (1.057)
1.0061.045 (1.008)1.029 (1.117)0.029βˆ’0.046 (1.005)βˆ’0.045 (1.003)
1.8811.903 (1.191)1.837 (1.116)0.8050.758 (1.037)0.737 (1.007)
0.7330.838 (1.024)0.828 (1.047)βˆ’1.267βˆ’1.326 (1.037)βˆ’1.296 (1.049)
0.6870.500 (1.012)0.506 (1.042)1.1451.053 (1.021)1.056 (1.024)
1.7281.760 (1.090)1.663 (1.148)βˆ’0.828βˆ’0.898 (1.048)βˆ’0.861 (1.107)
1.4291.582 (1.175)1.450 (1.085)0.7860.948 (1.203)0.876 (1.033)
0.8880.895 (1.023)0.893 (1.052)1.1161.137 (1.033)1.135 (1.017)
1.2231.346 (1.047)1.301 (1.117)βˆ’0.197βˆ’0.196 (1.005)βˆ’0.185 (1.010)
1.1551.348 (1.028)1.296 (1.049)1.2651.222 (1.260)1.187 (1.052)
1.5821.728 (1.085)1.673 (1.170)βˆ’0.708βˆ’0.856 (1.440)βˆ’0.838 (1.058)
1.4271.097 (1.019)1.084 (1.061)0.5130.426 (1.021)0.424 (1.003)
𝛼 2 𝜌 1 2
1.5041.722 (1.049)1.666 (1.079) 0.20.183 (1.199) 0.163 (1.038)
0.8861.047 (1.029)1.042 (1.022)
1.8291.792 (1.089)1.792 (1.033)
1.5781.589 (1.036)1.558 (1.023)
0.1310.088 (1.018)0.089 (1.007)
1.5621.888 (1.095)1.731 (1.019)
1.8331.616 (1.215)1.531 (1.008)
0.2100.190 (1.115)0.197 (1.023)
1.5331.635 (1.175)1.573 (1.003)
1.4361.309 (1.090)1.263 (1.057)
0.9610.879 (1.091)0.888 (1.039)
0.6780.807 (1.130)0.783 (1.106)
1.8882.341 (1.281)2.134 (1.055)
0.6180.744 (1.106)0.751 (1.013)
1.9671.921 (1.076)1.837 (1.034)
1.8621.934 (1.142)1.862 (1.060)
0.0620.135 (1.169)0.143 (1.060)
1.3891.223 (1.137)1.215 (1.041)