1 Building the Mx Script

Appendix  illustrates an example script for fitting a variance components model to twin pair covariance matrices for two like-sex twin pair groups. We estimate additive genetic, dominance genetic and random environmental variance components in the matrices A, D and E. The covariance statement is the same as for the path model example. The only change is in the calculation group, which does not square the estimates to construct A, C, E and D.