We will illustrate these steps through an example from our own work, namely the scoring of dimensions of internalizing behavior across three independent studies (also see P.J. Curran, J. McGinley, D.J. Bauer, A.M. Hussong, A. Burns, L. Chassin, K. Sher, R.A. Zucker, manuscript in preparation). This NIDA-funded project pools data from three existing longitudinal studies which oversampled offspring who had at least one biological, alcoholic parent and included matched controls of non-alcoholic parents. These three studies vary in the ages when assessments began, the number of waves and spacing of assessments, and methods of assessment among other dimensions. They include the Michigan Longitudinal Study (MLS; Zucker et al. , 2000), the Adult/Adolescent and Family Developmental Project (AFDP; Chassin et al., 1991), and the Alcohol, Health and Behavior Project (AHBP; Sher et al., 1991). Table 2 presents a summary of the pooled sample as a function of study membership, wave of assessment, and chronological age of participants. Each cell in the table identifies the number of individuals assessed in a given wave of a given study at a given age. The column totals identify the total number of individuals assessed at a given age pooling across study and wave.
