How to handle a nominal mediator is shown in our book Regression and Mediation Analysis using Mplus. An earlier description is given in the paper on our website:
Muthén, B. (2011). Applications of causally defined direct and indirect effects in mediation analysis using SEM in Mplus. Click here to download the paper. Click here to view the Technical appendix that goes with this paper and click here for the Mplus input appendix. Click here to view Mplus inputs, data, and outputs used in this paper.
Jon Heron posted on Tuesday, March 20, 2018 - 9:58 am
This post reminded me that we had grand plans to create a resource of Mplus code for causal mediation. Alas, the more we learned the more problems we discovered and this is yet to get off the ground.
We have worked this particular one out recently though, in the simpler case of binary nominal X and M, but with Y consisting of the ISQ from a growth model.
We opted for the BCH method in the end as our multivariate Y was pretty skewed.