I am trying to get a grip on the mxConstraint function. I played around with it a bit and encountered a strange thing. I fitted a model in which different parameters are constrained to be the same. When i specified this with the labels (i.e. both parameters are labeled "b11"), it worked fine.
However, when i try to do this with the mxConstraint function (i.e. the parameters are labeled "b11" and "b13", and I specified mxConstraint("b11"=="b13")), the parameter estimates change. Although the changes are very small I think this is strange. Another thing is that the estimates of all other parameters in the model change as well.
Does anyone have an idea, what could be a reason for this, and how I could overcome the problem?
Thanks for your help and greetings