Jon Elhai posted on Tuesday, April 07, 2009 - 12:39 pm
Is there a way to obtain a correlation matrix for an SEM model, including intercorrelations among all exogenous observed variables and latent factors within the model? I tried this using TECH4 but the matrix only reports correlations for latent factors and endogenous observed variables. I'm using WLSMV estimation with binary and continuous observed variables.
It is not straighforward to get this info via WLSMV estimation. You can turn your exogenous observed variables (which Mplus calls "x's") into "y's" by mentioning say their means. But note that this changes your model assumptions because then you need to assume underlying normality also for these x's - that is, you cannot benefit from the less stringent Mplus assumption of conditional underlying normality for the y's and no distributional assumption for the x's.
Catherine posted on Wednesday, March 09, 2011 - 4:28 am
I have a question about the correlation matrix Mplus produces. This correlation matrix dramatically differs from the correlation matrix SPSS produces. Where do these differences come from, and wich one should I use?
The differences could be that the type of correlations differ between the two programs, for example, if you are using WLSMV with binary variables in Mplus you will obtain tetrachoric correlations. In SPSS, you will obtain Pearson correlations. Also, the sample sizes most likely differ. If this does not clear things up for you, please send both the Mplus and SPSS outputs and your license number to firstname.lastname@example.org.
See Examples 13.1 and 13.2 and pages 510-511 of the user's guide.
Stephanie posted on Saturday, November 30, 2013 - 7:57 am
I have a question regrading the correlation matrix in MPlus. As my dependent variable is dichotomous I am using the WLSMV estimator. Furthermore the model contains other dichotomous as well as continuous variables and additionally two latent contructs. Now I need to calculate the correlation matix and the levels of significance. I ran a TYPE=BASIC in the analysis command as well as a SAMPSTAT in the output command, but I am not sure, where the levels of significance are reportet. Could you please give me advice where I can find them? Besides, I am not sure if it is possible to calculate the correlations between the latent contructs an all other variables in the model? I thank you very much for your kind support!
Sorry if this is answered elsewhere but I can't find it. In a straightforward CFA with continuous variables, how do I obtain the correlations/covarainces of the observed varaibles and the factors. I don't want the partial correlations (factor loadings) but the full ones (what they would be with the predicted values for the factors). Thank you!
The first statement gives the (invisible) unit loading in y = fy and the second statement gets rid of the residual variance in y = fy which instead appears in the variance of f. The rest of the modeling then uses fy instead of y. So for instance
f BY fy ....
Just make sure that the fy's don't also have correlation parameters with the "real" factors (check TECH1).
The unstandardized results and r-squares are all identical between models. But the standardized results are different. However, this seems to be a scaling problem.
To get the right standardized results (factor loadings) I had to multiply the factor loading of y onto fy by the factor loading of fy onto f (using your example above); then I get the identical answer as the original reported factor loading of y onto f. However, from the correlations in TECH4 I cannot recover the correct estimates through any multiplication that I can figure out.