title: Challenges in quantifying marijuana use.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Gray
authors.forename: Noreen L
authors.initials: NL
authors.lastname: Watson
authors.forename: Douglas K
authors.initials: DK
authors.lastname: Christie
mesh_terms: D006801:Humans; D002189:Marijuana Abuse / Q000175:diagnosis*; D015813:Substance Abuse Detection / Q000379:methods*