From the available data for each subject in COGA and MOTWIN, we derived and utilized personal identifiers, demographic data (gender, race, and birth year), zygosity (for MOTWIN), a polychotomous index of familial liability to antisocial development; and presence or absence of antisocial outcome in the children. All of the research information except the identifiers was encrypted. The encrypted information was submitted with identifiers to the DSS, where it was cross-referenced with official-report records at an individual level, and the linked data set was subsequently stripped of individual identifiers before returning to the research team.
