The simulations were carried out using the software package . For each replicated data set, we computed the twin correlations for the latent scores, the twin correlations of the sum scores and the twin correlations for the log-transformed sum scores. The three types of analyses were carried out in WinBUGS. After a burn-in phase of 1000 iterations, the characterisation of the posterior distribution for the model parameters was based on 1000 iterations from 2 independent Markov chains. From each of the 3 (analyses) * 101 (replicated data sets) marginal posterior distributions for the heritability we took the mean and the median as point estimates.
