I have a path model with dichotomous predictor and outcome variables and dichotomous and three and four category ordinal mediator variables. My problem is the interpretation of the probit coefficients. I wanted to standardise the data before entry, but I believe this is not possible in mplus as it leads to non-integer numbers for the categories. What is the best way to compare the effects of the different mediator scales and particulalry considering the indirect effects? I cannot find the solution to this question in exisitng research, questions/answers so any advice would be gratefully received.
You should not standardize categorical variables. You can use weighted least squares and MODEL INDIRECT to obtain indirect effects. If you also ask for the STANDARDIZED option in the OUTPUT command, you will obtain standardized indirect effects.