
Message/Author 


Dear Dr. Muthen, I have a nominal (4 groups) mediator with both X and Y continuous. I just read you paper (Muthen, 2011) and I am just confused as to how parameters were fixed in Tables 4849, and if a similar "fixing" approach is possible for a group of 4 instead of 3. Thank you for our time. https://www.statmodel.com/download/CausalmediationPaperMplus%20input%20appendix.pdf Mark Match 


Not sure what you mean  no parameters are fixed there. The setup can be generalized to other number of mediator categories in a straightforward manner. But it does involve being able to handle the Model Constraint formulas. 


I apologize for the confusion. I meant to say freeing parameters (e.g., y*.75), or at least that was my understanding. I believe I have an understanding on the formulas and labels, but I ma not sure how to deal with the '*', or if I have too. I hope I am making some sense. (Model section from Table 48) [c#1*1] (gamma01); [c#2*.5] (gamma02); c#1 ON x*.7 (gamma11); c#2 ON x*.3 (gamma12); y ON x*0; y*.75; %c#1% [y*2] (beta01); y ON x*.5 (beta11); %c#2% [y*0] (beta02); y ON x*.3 (beta12); %c#3% [y*2] (beta03); y ON x*.2 (beta13); 


Ah, those * values are just starting values that I chose to match the simulated data  you don't need to give any such values. Btw, what is your nominal mediator? 


Thank you Dr. Muthen. I have extended the equation to include 4 groups, but I must be doing something wrong (possibly with the summation) since I have very big estimates and standard errors for some parameters (p21, p31, p41, term11, term01, tie, total, pie), which I did not obtain when I run my data with your code of 3 groups only. My nominal variable is acculturation group. Would it be possible to post here what I am doing for clarification purposes? 


Please send the relevant files and your license number to support@statmodel.com. 

Back to top 

