Error Message and Output Query PreviousNext
Mplus Discussion > Structural Equation Modeling >
Message/Author
 Lucy Hobby posted on Tuesday, September 20, 2011 - 7:48 pm
I have some questions regarding a model I have been conducting for my research, and the output it is producing. In this model, I want to control for cultural background (Culture), and then using a contrast variable (contrast) containing two groups of interest, predict academic self-concept (ESCT) and academic achievement (EACH) at Time 1 and Time 2. The most relevant syntax is produced below:
ESCT2 ON Culture ESCT1 EACHT1 contrast;
ESCT1 ON Culture contrast;
EACHT2 ON Culture EACHT1 ESCT1 contrast;
EACHT1 ON Culture contrast;
When I try to run this model with the culture and the contrast variable correlated (culture with contrast;), the following error message is produced:
THE STANDARD ERRORS OF THE MODEL PARAMETER ESTIMATES MAY NOT BE TRUSTWORTHY FOR SOME PARAMETERS DUE TO A NON-POSITIVE DEFINITE FIRST-ORDER DERIVATIVE PRODUCT MATRIX. THIS MAY BE DUE TO THE STARTING VALUES BUT MAY ALSO BE AN INDICATION OF MODEL NONIDENTIFICATION. THE CONDITION NUMBER IS 0.133D-18. PROBLEM INVOLVING PARAMETER 101.
continued
 Lucy Hobby posted on Tuesday, September 20, 2011 - 7:50 pm
Ive tried to get around this error by specifying alterations in the syntax (more specifically, how Culture and contrast are associated with each other). Following are a list of the models run with the exact same syntax except for what is listed below), all of which produce the same statistical output (chi-square, degrees of freedom, and predictive paths are all the same), but one model receives the above error.
Focusing only on what is modified in the syntax:
Model 1 Culture with contrast; (error)
Model 2 !Culture with contrast; (no error)
Model 3 contrast on Culture; (no error)
Model 4 Culture on contrast; (no error)
When I run the same model without the correlation between culture and contrast specified, I receive no error message and the same chi-square, df, and predictive path values. I am assuming this is because the correlation is a default in mplus. Now, if I run the same model with culture predicting contrast (Contrast on culture;) or contrast predicting culture (Culture on contrast;), I also receive no error message and the same chi-square, df, and predictive path values as the above two models.
Im wondering why I receive the error message when running the model where the variables are correlated, and why Im getting the exact same statistical results across all four models?
 Linda K. Muthen posted on Wednesday, September 21, 2011 - 7:58 am
Please send the output with the error and your license number to support@statmodel.com. Please limit your posts to one window.
Back to top
Add Your Message Here
Post:
Username: Posting Information:
This is a private posting area. Only registered users and moderators may post messages here.
Password:
Options: Enable HTML code in message
Automatically activate URLs in message
Action: