title: Sampling and coverage difficulties in Canadian drug use surveys and efforts to avoid them.
mesh_terms: D000293:Adolescent; D000437:Alcoholism / Q000453:epidemiology; D003430:Cross-Sectional Studies; D004812:Epidemiologic Methods; D006801:Humans; D002189:Marijuana Abuse / Q000453:epidemiology; D009864:Ontario; D011619:Psychotropic Drugs; D012494:Sampling Studies; D019966:Substance-Related Disorders / Q000453:epidemiology*
chemical_list: D011619:Psychotropic Drugs