I am doing a study using structural equation modelling. I adopted the two-step approach according to Anderson and Gerbing (1988) and now currently construct CFA models for comparison.

I am really confused by fully constrained and unconstrained models. I understand that I can constrain some of the parameters to zero or one to make them fixed (constrained).

**My question is (1) Why do I need to constraint these parameters?

(2) How do I know which one (covariance) I should constrain? To zero or to one?**

Much appreciated your help and guidelines XD



1 Answer 1


When you draw a path diagram that makes a model, what you are doing is constraining parameters. Think of the process of drawing a path diagram as starting with a diagram that has every possible parameter (arrow) on it, and then deleting most of them.


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