Can a grouping variable change over t... PreviousNext
Mplus Discussion > Structural Equation Modeling >
 Paraskevas Petrou posted on Monday, March 12, 2012 - 3:35 am

I am testing a multilevel structural equation model with a 3-wave longitudinal dataset. I have nested all three measurements within individuals and all the paths I am interested in include within-level variables. I would now like to perform group analysis to my data. So I would like to see if the coefficients are different between group 1 and group 2 of the sample. The problem is that the grouping variable is also a within-level variable and is changing over time. So its value can be either 1 or 2 across times 1-3. How can I do that with Mplus?

Thank you in advance.

Kind regards,
Paris Petrou
 Linda K. Muthen posted on Monday, March 12, 2012 - 1:16 pm
You should use the grouping variable as a dummy time-varying covariate.
 Paraskevas Petrou posted on Wednesday, March 14, 2012 - 8:37 am
Thank you very much Linda.

The reason why I need to do that is because I am using an incogruence score between A and B (both within-level variables) as a predictor in my model. I am more interested in the incogruence than the interaction between the two variables. But in order to address criticisms around the use of incogruence scores, I would need to perform my analyses for two groups: Group 1: A > B and Group 2: A < B.

If I use the grouping variable as a dummy time-varying covariate, I will control for its effect, but I will still not be able to compare the results between group 1 and group 2.

The only way to do that is to create an interaction between my incogruence score and the covariate? But this is too complicated and I am not sure what that variable would mean. Then it would be better to use an interaction term all the way from the start, right?

 Bengt O. Muthen posted on Wednesday, March 14, 2012 - 6:31 pm
I don't understand this type of data setting well enough to answer. You may want to ask the question on SEMNET.
 Paraskevas Petrou posted on Friday, March 16, 2012 - 1:52 am
OK, thank you.
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