multi-level application of the model (adapted from https://github.com/OpenMx/OpenMx/blob/master/inst/models/nightly/mplus-ex9.12.R) was implemented to account for the non-independence of observations in samples that included relatives by design (COGA, FinnTwin12, FTC). As >90% of participants in each cohort had initiated alcohol use before or during the assessment timeframe, no observations were removed for missing phenotypic values; individuals were coded with a frequency of zero at each non-drinking wave.
