PURPOSE/OVERVIEW: This chapter presents the results of a special follow-up survey of persons who did not respond to the 1990 National Household Survey on Drug Abuse (NHSDA). The aim was to understand the reasons people chose not to participate, or were otherwise missed
in the survey, and to use this information in assessing the extent of the bias, if any, that nonresponse introduced into the 1990 NHSDA estimates.
