I have two measures. One is a global measure of a construct, the other is a domain specific measure of the construct. I'm trying to show that they a different, but related.
So, I've conducted CFA to test a 1-factor model (all items from both scales) and a two factor model (half of the items from the global measure, the other half from the domain specific measure), as well as a 4-factor model (the global measure is sometimes reported to contain 2 factors itself, so I tested a 4 factor model with 2 subscales from the global measure and 2 subscales from the domain specific measure).
I am unsure whether to examine their fit indices visually and let that inform my hypothesis, or to nest the models and compare them that way. Any guidance would be much appreciated!