Variance in and covariance between cannabis involvement and those aspects of STB that remained associated with it, after adjustment for confounding, was decomposed into additive genetic (A), shared environmental (C) or non-additive genetic (D) and individual-specific environmental (E) factors (Neale and Cardon, 1992). As there is evidence for an ACE model for cannabis involvement and an ADE model for SI, both were tested and compared using their −2 loglikelihood fit.
