title: The Cannabis Problems Questionnaire: factor structure, reliability, and validity.
abstract: OBJECTIVE
  To develop a multi-dimensional valid and reliable measure of cannabis-related problems.
  
  
  METHODS
  The Cannabis Problems Questionnaire (CPQ) was developed from the Alcohol Problems Questionnaire to measure cannabis treatment outcome. The CPQ was administered on two occasions 1 week apart to a stratified sample of adults who had used cannabis at least once in the previous 3 months. Exploratory factor analyses were conducted and the relationship between items of the CPQ and measures of daily use and dependence assessed. The reliability of the CPQ was also assessed using a test-retest and inter-rater reliability methodology.
  
  
  RESULTS
  Exploratory factor analyses revealed a three factor solution best described the data accounting for 57% of the variance in the larger item set. The CPQ is highly reliable with test-retest tetrachoric correlations of between 0.92 and 1.00 and inter-rater reliability correlations between 0.74 and 1.00. The total CPQ score classified DSM-IV cannabis dependence with 84% specificity and sensitivity and daily cannabis use with 83% specificity and 55% sensitivity.
  
  
  CONCLUSIONS
  The 22-item CPQ is a valid, reliable and sensitive measure of cannabis-related problems for use with clinical and research populations of current cannabis users.
authors.affiliation: National Drug and Alcohol Research Centre, University of New South Wales, Sydney, NSW 2052, Australia. J.Copeland@unsw.edu.au
authors.forename: Jan
authors.initials: J
authors.lastname: Copeland
authors.forename: Stuart
authors.initials: S
authors.lastname: Gilmour
authors.forename: Peter
authors.initials: P
authors.lastname: Gates
authors.forename: Wendy
authors.initials: W
authors.lastname: Swift
mesh_terms: D000293:Adolescent; D000328:Adult; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000453:epidemiology* / Q000523:psychology* / Q000628:therapy; D008875:Middle Aged; D011594:Psychometrics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires; D016896:Treatment Outcome