SPSS Hessian Matrix Error - Help!

Posted by Stolz100 on Apr 04, 2014; 3:58pm
URL: http://spssx-discussion.165.s1.nabble.com/SPSS-Hessian-Matrix-Error-Help-tp5725300.html

I am trying to conduct a linear growth model in SPSS using mixed models. We conducted a training study where participants (interviewers) conducted 10 weeks of interviews with children, receiving regular peer-review. Our dependent measures are their questioning techniques, and how they might change over time (e.g. does the proportion of yes-no questions decrease?; defined as a variable of their proportion of yes-no questions each week, for ten weeks).

When I run the model in SPSS, I get an error stating the following: The final Hessian matrix is not positive definite although all convergence criteria are satisfied. The MIXED procedure continues despite this warning. Validity of subsequent results cannot be ascertained.
 
In addition, on the estimates of covariance parameters, I get the following error: This covariance parameter is redundant. The test statistic and confidence interval cannot be computed.

I have tentatively conducted a one-way ANOVA to assess whether there is level 2 variation in my outcome, and there is. This was significant at p < .001.

I am unsure why I am receiving the current error for the growth model and would like to solve the problem. Here is my syntax:

Please help!


MIXED YN_Proportion WITH Interview_Number
  /CRITERIA=CIN(95) MXITER(100) MXSTEP(10) SCORING(1) SINGULAR(0.000000000001) HCONVERGE(0,
    ABSOLUTE) LCONVERGE(0, ABSOLUTE) PCONVERGE(0.000001, ABSOLUTE)
  /FIXED=Interview_Number | SSTYPE(1)
  /METHOD=ML
  /PRINT=CPS CORB DESCRIPTIVES  SOLUTION TESTCOV
  /RANDOM=INTERCEPT Interview_Number | SUBJECT(Participant) COVTYPE(ARH1).