Adding/Subtracting Two Latent Factors PreviousNext
Mplus Discussion > Confirmatory Factor Analysis >
 Thomas Scotto posted on Friday, December 06, 2013 - 5:49 pm

VIA CFA with ordinal indicators and the WLSMV estimator, I've obtained two latent variables of concepts that are of interest to me, say X and Y. Fit of the model is excellent, and I'd like to move on to full SEM where I test the following--A large gap between the respondent's location on factor X and their location on Factor Y drives evaluations of Z. I have read up on the warnings associated with using saved factor scores in a separate analysis, so is there a way to combine factors in an additive or subtractive manner?


 Bengt O. Muthen posted on Friday, December 06, 2013 - 6:15 pm
Would it work to consider

Z = a + b *(X-Y ) + e

and say


Z ON X (posb)
Y (negb);

Model Constraint:
0 = posb+negb;
 Thomas Scotto posted on Saturday, July 19, 2014 - 5:02 pm

Sorry to be delayed before coming back to this. I'm not really clear on the logic here?

As an output with the constraint, I receive

Z on
X 1.044
Y -1.044

I need the direct effects of X and Y and the interactive effects

Perhaps an easier way would be to create another latent variable that somehow is the difference between the two and then use all three in the path model. Can this be done?

I thought one way might be to try to do something similar to latent change modelling and introduce a phantom difference factor, but I'm not sure I'm on solid ground.


 Thomas Scotto posted on Saturday, July 19, 2014 - 5:29 pm

After writing, I realised my language was unclear. What I mean to say is I need the effects of the difference between x and y on z. I do NOT want to interact the two factors.

 Bengt O. Muthen posted on Sunday, July 20, 2014 - 6:25 am
You can do what you suggest.
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