· NHSDA drug use prevalence estimates for specific subgroups are sometimes based on modest to small sample sizes, which may lead to substantial sampling error.
· Population projections prepared for the U.S. Bureau of the Census' Current Population Survey (and used in weighting the 1998 NHSDA sample) are subject to error, which increases with the age of the last census.
· The population surveyed consists of noninstitutionalized
civilians living in households, college dormitories, homeless shelters,
rooming houses, and on military installations. Therefore, this report does
not present estimates for some segments of the U.S. population that may
contain a substantial proportion of drug users, such as transients not
residing in shelters (e.g., users of soup kitchens or residents of street
encampments) and those incarcerated in county jails or State and Federal
This page was last updated on June 03, 2008.