Regression analysis in the presence of heterogeneous intraclass correlations

In the statistical analysis of twinship and familial data, one often encounters the need for regression methods that control for the possibly different aggregation of the twins and the members of the families according to their type (e.g., monozygotic, dizygotic for twinship data). We present the maximum likelihood solution for the regression analysis of data in the presence of heterogeneous intraclass correlations. This work extends previous results for the case of a homogeneous intraclass correlation. An application of the methods for the analysis of twinship data is included.