title: Methodological issues in drug usage surveys: anonymity, recency, and frequency.
mesh_terms: D000328:Adult; D002188:Cannabis; D003417:Criminal Psychology; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D012649:Self Concept; D013334:Students; D019966:Substance-Related Disorders / Q000145:classification / Q000453:epidemiology*; D011795:Surveys and Questionnaires; D014481:United States; D014495:Universities