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Bayesian MIRT w Log-Normal Prior |
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I have a question about the use of log-normal priors in Bayesian MIRT recommended by Patz & Junker (1999). When I try to specify this prior, I get the following warning message: *** FATAL ERROR THE PRIOR SPECIFICATION FOR PARAMETER 1 IS NOT AVAILABLE. This warning appears for all priors except normal. I must be missing something, so any insight is appreciated. I've attached my code below. Thanks! Ryan DATA: FILE IS Wave1.dat; FORMAT IS Free; VARIABLE: NAMES ARE v1 v2 v871 v875 v879 v883 v887 v891 v895 v871r v875r v879r v883r v887r v891r v895r; USEVARIABLES ARE v871r-v895r; CATEGORICAL ARE v871r-v895r; CLUSTER IS v2; MISSING ARE ALL(-9); ANALYSIS: TYPE IS COMPLEX; ALGORITHM IS GIBBS(RW); ESTIMATOR IS BAYES; FBITERATIONS ARE 5000; THIN IS 100; PROCESSORS ARE 8; MODEL: F1 BY v883r* v887r* v891r* (a1-a3); F2 BY v871r* v875r* v879r* (b1-b3); F3 BY v895r* (c1); [F1@0 F2@0 F3@0]; F1@1; F2@1; F3@1; MODEL PRIORS: a1-a3 ~ LN(0,.5); b1-b3 ~ LN(0,.5); c1 ~ LN(0,.5); OUTPUT: STDYX; RESIDUAL; TECH8; PLOT: TYPE IS PLOT2; |
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The LN prior is for variances. See page 620 of the user's guide. |
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