Hello

My data of cognitive measures is indicating a number of violations of the assumptions of the twin model. I have transformed the data using z scores and still find that MZ and DZ variances are different. Any ideas on how I should proceed, including how to adjust the script in the ACE/ADE model to deal with this?

Many thanks

Karen

Essentially, you take the twin expectations and pre & post multiply by a matrix with causal paths between the twins in it. So if you had

It might become

You'd need to include the matI and matB objects in the mxModel() of course. And change the expCovDZ formula in exactly the same way (with the same I and B matrices).