I am unclear as to how Mplus treats variables in a dataset that are named in the USEVARIABLES option but are not included in the MODEL command. I have heard from some colleagues that this technique has the effect of "controlling" for a variable in the analysis model, but they have not been able to provide a definitive explanation of how this would work.
I have not found any information on this technique in the user guide. According to previous posts in these discussion boards, I see that "any variable on the USEVARIABLES list is used in model estimation whether it is mentioned in the MODEL command or not." Can you provide additional explanations or insights into how these variables are treated and how they affect the rest of the model?
All variables on the USEVARIABLES list are used in the analysis. If they are not mentioned in the MODEL command, means and variances are estimated for them. You will receive the following message in the output:
*** WARNING in MODEL command Variable is uncorrelated with all other variables: Y4 *** WARNING in MODEL command Variable is uncorrelated with all other variables: Y5 *** WARNING in MODEL command Variable is uncorrelated with all other variables: Y6