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Multilevel MIRT random item effects m... |
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Hi Dr. Muthen, I tried to fit a MMIRT random item effects model to the PISA student achievement data. The error message I received is as follows: THE MODEL ESTIMATION DID NOT TERMINATE NORMALLY. THE PSI MATRIX IS NOT POSITIVE DEFINITE. THE PROBLEM OCCURRED IN CHAIN 2. PROBLEM INVOLVING VARIABLES U1 AND . THE PROBLEM OCCURRED ON THE WITHIN LEVEL. Will you please tell me why the model didn't work? Thank you! SW Data: File is pisa12book7a_math_short.csv; Variable: Names are counid stid u1 u2 u3 u4 u5 u6 u7 u8 u9 u10 u11; Usevariables = u1-u11; Missing are all (7,8,9); Categorical = u1-u11; Cluster = counid; Analysis: Type = twolevel random; Process = 2; Estimator = bayes; Thin = 100; Model: %within% s11-s16|f1 by u2* u3 u6 u8 u9 u10; s21-s23|f2 by u4* u5 u6; s31-s34|f3 by u1* u2 u7 u11; f1-f3@1; %between% f1 u2 u3 u6 u8 u9 u10 s11-s16; f2 u4 u5 u6 s21-s23; f3 u1 u2 u7 u11 s31-s34; Output: tech1 tech8 stdy; |
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Please send output and data to support along with your license number |
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