title: Surveying alcohol and other drug use through telephone sampling: a comparison of landline and mobile phone samples.
abstract: BACKGROUND
  Telephone surveys based on samples of landline telephone numbers are widely used to measure the prevalence of health risk behaviours such as smoking, drug use and alcohol consumption. An increasing number of households are relying solely on mobile telephones, creating a potential bias for population estimates derived from landline-based sampling frames which do not incorporate mobile phone numbers. Studies in the US have identified significant differences between landline and mobile telephone users in smoking and alcohol consumption, but there has been little work in other settings or focussed on illicit drugs.
  
  
  METHODS
  This study examined Australian prevalence estimates of cannabis use, tobacco smoking and risky alcohol consumption based on samples selected using a dual-frame (mobile and landline) approach. Respondents from the landline sample were compared both to the overall mobile sample (including respondents who had access to a landline) and specifically to respondents who lived in mobile-only households. Bivariate comparisons were complemented with multivariate logistic regression models, controlling for the effects of basic demographic variables.
  
  
  RESULTS
  The landline sample reported much lower prevalence of tobacco use, cannabis use and alcohol consumption than the mobile samples. Once demographic variables were adjusted for, there were no significant differences between the landline and mobile respondents on any of the alcohol measures examined. In contrast, the mobile samples had significantly higher rates of cannabis and tobacco use, even after adjustment. Weighted estimates from the dual-frame sample were generally higher than the landline sample across all substances, but only significantly higher for tobacco use.
  
  
  CONCLUSIONS
  Landline telephone surveys in Australia are likely to substantially underestimate the prevalence of tobacco smoking by excluding potential respondents who live in mobile-only households. In contrast, estimates of alcohol consumption and cannabis use from landline surveys are likely to be broadly accurate, once basic demographic weighting is undertaken.
authors.affiliation: Drug Policy Modelling Program, National Drug and Alcohol Research Centre, University of New South Wales, Sydney, Australia. michaell@turningpoint.org.au
authors.forename: Michael
authors.initials: M
authors.lastname: Livingston
authors.forename: Paul
authors.initials: P
authors.lastname: Dietze
authors.forename: Jason
authors.initials: J
authors.lastname: Ferris
authors.forename: Darren
authors.initials: D
authors.lastname: Pennay
authors.forename: Linda
authors.initials: L
authors.lastname: Hayes
authors.forename: Simon
authors.initials: S
authors.lastname: Lenton
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D019973:Alcohol-Related Disorders / Q000453:epidemiology*; D001315:Australia; D015982:Bias; D040421:Cell Phone / Q000706:statistics & numerical data*; D003625:Data Collection / Q000379:methods*; D003710:Demography; D005260:Female; D015438:Health Behavior; D006306:Health Surveys; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D002189:Marijuana Abuse / Q000453:epidemiology*; D008875:Middle Aged; D012494:Sampling Studies; D057566:Self Report; D012907:Smoking; D013689:Telephone / Q000706:statistics & numerical data*; D055815:Young Adult