Research Article

A Gibbs Sampler for the Multidimensional Item Response Model

Table 2

Posterior estimates and Gelman-Rubin 𝑅 statistics for 𝛼 1 , 𝛼 2 , 𝛽 , and 𝜌 1 2 when the specified intertrait correlation is 0.4 (chain length = 10,000, burn-in = 5,000).

TrueUniform priors Normal priorsTrueUniform priors Normal priors
Estimate ( 𝑅 )Estimate ( 𝑅 )Estimate ( 𝑅 )Estimate ( 𝑅 )

𝛼 1 𝛽
0.9050.977 (1.177)0.918 (1.018)βˆ’1.433βˆ’1.640 (1.035)βˆ’1.583 (1.035)
0.3100.311 (1.138)0.297 (1.076)βˆ’1.552βˆ’1.790 (1.024)βˆ’1.739 (1.035)
0.6050.609 (1.170)0.575 (1.057)βˆ’0.656βˆ’0.676 (1.039)βˆ’0.664 (1.027)
0.1170.116 (1.291)0.096 (1.071)βˆ’0.146βˆ’0.303 (1.035)βˆ’0.297 (1.004)
0.1970.243 (1.005)0.257 (1.006)βˆ’1.206βˆ’1.278 (1.004)βˆ’1.280 (1.004)
0.4980.583 (1.141)0.551 (1.065)βˆ’1.457βˆ’1.567 (1.046)βˆ’1.549 (1.021)
0.4420.371 (1.152)0.356 (1.073)1.9042.013 (1.345)1.830 (1.519)
1.0060.897 (1.020)0.896 (1.021)0.029βˆ’0.004 (1.010)βˆ’0.003 (1.000)
1.8812.120 (1.007)1.998 (1.361)0.8050.788 (1.040)0.775 (1.197)
0.7330.712 (1.126)0.695 (1.113)βˆ’1.267βˆ’1.363 (1.029)βˆ’1.353 (1.048)
0.6870.710 (1.070)0.692 (1.075)1.1451.100 (1.007)1.104 (1.006)
1.7282.277 (1.176)2.026 (1.091)βˆ’0.828βˆ’1.034 (1.132)βˆ’0.951 (1.131)
1.4291.561 (1.081)1.495 (1.075)0.7860.698 (1.045)0.692 (1.012)
0.8881.071 (1.006)1.028 (1.068)1.1161.109 (1.005)1.096 (1.004)
1.2231.226 (1.230)1.175 (1.036)βˆ’0.197βˆ’0.397 (1.021)βˆ’0.386 (1.042)
1.1551.185 (1.022)1.115 (1.174)1.2651.017 (1.094)1.005 (1.020)
1.5821.450 (1.039)1.451 (1.050)βˆ’0.708βˆ’0.679 (1.035)βˆ’0.681 (1.005)
1.4271.714 (1.062)1.667 (1.110)0.5130.476 (1.069)0.477 (1.048)
𝛼 2 𝜌 1 2
1.5041.417 (1.045)1.375 (1.114) 0.40.434 (1.288) 0.425 (1.058)
0.8861.011 (1.045)0.968 (1.103)
1.8291.620 (1.013)1.621 (1.127)
1.5781.660 (1.069)1.628 (1.015)
0.1310.084 (1.012)0.081 (1.011)
1.5621.430 (1.053)1.419 (1.038)
1.8332.199 (1.342)1.942 (1.335)
0.2100.114 (1.065)0.126 (1.155)
1.5331.497 (1.097)1.495 (1.093)
1.4361.372 (1.054)1.371 (1.025)
0.9610.996 (1.025)1.014 (1.132)
0.6780.456 (1.115)0.486 (1.212)
1.8881.622 (1.152)1.631 (1.071)
0.6180.437 (1.073)0.461 (1.108)
1.9671.781 (1.129)1.780 (1.290)
1.8621.502 (1.093)1.517 (1.047)
0.0620.121 (1.083)0.138 (1.237)
1.3891.320 (1.073)1.348 (1.198)