Efficacies of recruiting subjects for association studies (and comparison with recruitment for linkage based studies): Little currently-available data documents the features of drug abuse research volunteers who might consent to participate in molecular genetic studies for linkage or association. We thus describe the details of the recruitment of subjects for these studies at the NIH (IRP) facility in Baltimore, MD during a 30 month period (J H, GRU et al, unpublished observations). During this period, 13,969 individuals were screened by telephone and 2633 were interviewed in person for all (genetic and nongenetic) studies at this research facility. These individuals were 68% African American, 29% European American, 1% Hispanic and 72% male, with average age 35.
