Abstract
The increasing use of family samples from “normal” populations (as opposed to clinical samples) in substance abuse research raises concern about the validity of responses from participating families. Nonpartici-pating families may have greater numbers of substance users who wish to conceal problems, when compared to families which cooperate with researchers. Unobtrusive analyses of institutional records of a health maintenance organization comparing families agreeing to participate in a substance use study (N = 508) with those families unwilling to participate (N = 538) reveal no significant differences in the use of chemical dependency services between the two groups. Surveys of the non-participating families indicate that the major reasons for noncoopera-tion were the lack of time and inconvenience in getting family members together. These findings suggest the feasibility of sampling families from normal populations.