bivariate moderation models in the context of data in which the covariance between M and T is moderated. These simulations are of specific interest since moderator-dependent variation in the strength of the covariance between M and T is not well accommodated by the estimated regression parameters β 0,MZ, β 1,MZ, β 2,MZ, β 0,DZ, β 1,DZ, and β 2,DZ in Eqs. 8 and 9, and problems are therefore to be expected for the extended univariate moderation model.
