Message/Author 


Hello Drs. Muthen, I am running a path analysis, specifically a mediated moderation using the following model: MODEL: VAS3_anx ON VAS1_anx cfne_m ccond fnexcond; IAT_TR on VAS3_anx; where VAS3_anx is mood state at time 2, VAS1_anx is mood state at time 1, cfne_m is a measure of social anxiety, ccond is condition, fnexcond is the mood condition and social anxiety interaction term and IAT_TR is tension reduction cognitions. I am consistently getting CFI values at 1 and TLIs above one and am pretty sure my model is not saturated. How do I interpret these CFI values, especially given the fact the VAS3_anx to IAT_TR relation is nonsignificant? Thank you 


What is your chisquare value and pvalue and how many degrees of freedom does the model have? 


I have 4 dfs, and the pvalue is 0.0000, with a CFI of 1.000 and a TLI of 1.054. 


Oops, sorry, my Chi square is 1.139, p=0.888. for the baseline model it is 127.366, df=9, p=0.0000 the P value for IAT_TR on VAS3_anx is .590. 


So your model fits very well given the chisquare pvalue and CFI and TLI. This can also happen if you have very low sample correlations and a very small sample size with low power to reject the model. 

Guanyi Lu posted on Wednesday, May 30, 2012  8:02 am



Hi Dr. Muthen, I am testing a moderated mediation model. I use "xwith" to create the interaction term (one continuous latent and one observed continuous). "type=random" was used. bootstrapping + confidence interval were used to test mediation effects. Mplus 6.21 gave me an error message stating that "model indirect" cannot be used with "type=random". However, "xwith" can only be used with "type=random". I wonder is there a way to test mediation effects while keeping the interaction term (xwith command) in my model? in other words, can I test both mediation and moderation in ONE model using Mplus? Best, Komen 


You can use MODEL CONSTRAINT to specify the indirect effects. See the user's guide for further information. 

Guanyi Lu posted on Wednesday, May 30, 2012  12:11 pm



Thanks Linda. Using "bootstrapping and bias corrected CI" (the method proposed by Hayes and Preacher) to test mediation is recommended by the reviewers. I want to stick to this method. If I use "model constraint" and "bootstrapping + bias corrected CI", I guess I will get CIs for the indirect effects specified. Are those CIs equivalent to CIs which are produced by Mplus when the interaction term is not introduced? 


The confidence intervals with and without the interaction will not be the same. The model has changed. 


Hello Dr. Muthen, I also have question regarding mediated moderation with MPLUS. My data comes from an experimental design (IV and Moderator are manipulated variables, each has two conditions) and I want to calculate a model with the following variables: 1 IV (observable, categorial, two groups), 1 Moderator (observable, categorial, two groups), 1 Mediator (latent, continuous), 3 DVs (each continuous and latent). The moderator influences the path from the IV to the Mediator. I found an instruction that equals to Model 7 in PROCESS Macro: http://offbeat.group.shef.ac.uk/FIO/model7.htm However, as I am not very familiar with MPLUS yet, I am not sure, if this is the right way. Another problem is that I can only include 1 DV in the model. But I am interested in simultaneously estimating the model with all 3 DVs (if this is possible at all). Thanks in advance!!!! Best Kathrin 


To handle a binary moderator you can either create a product of variables in Define or use multiplegroup analysis. These types of models are discussed in our new book: http://www.statmodel.com/Mplus_Book.shtml See also http://www.statmodel.com/Mediation.shtml 


Hi Dr. Muthen, I would like to test an indirect effect whereby the IV is an interaction between a manifest variable (a dichotomous experimental manipulation) and a continuous latent variable (to test for mediated moderation). The mediator and DV are both continuous latent variables. Is this possible? It seems that the MODEL INDIRECT command does not work when TYPE=RANDOM. Is this model possible? Thanks for any help. 


You need to use MODEL CONSTRAINT to specify the indirect effect in this case. 

Back to top 