title: Improving the self reporting of tobacco use: results of a factorial experiment.
abstract: OBJECTIVE
  To examine divergent estimates of smoking prevalence in two random digit dial surveys for the same population. Based upon internal and external reviews of survey procedures, differences in survey introductions (general health versus tobacco specific introduction) and/or differences in the use of filter questions were identified as the most likely explanations. This prompted an experiment designed to investigate these potential sources of measurement error.
  
  
  METHODS
  A randomised 2 x 2 factorial experiment.
  
  
  METHODS
  A random digit dial telephone survey from July to September 2000.
  
  
  METHODS
  3996 adult Californian respondents.
  
  
  METHODS
  A series of smoking prevalence questions in the context of a tobacco or general health survey.
  
  
  RESULTS
  Logistic regression analyses suggest that, among females, prior knowledge (from the survey introduction) that a survey is concerned with tobacco use may decrease self reported smoking prevalence (approximately 4% absolute prevalence difference). Differences in the use of filter questions resulted in almost no misclassification of respondents.
  
  
  CONCLUSIONS
  The tobacco specific survey introduction is causing some smokers to deny their tobacco use. The data suggest that these smokers tend to be women that smoked occasionally. A desire by the participants to minimise their personal time costs or a growing social disapproval of tobacco use in the USA may be contributing to the creation of previously undetected survey artefacts in the measurement of tobacco related behaviours.
authors.affiliation: Tobacco Control Section, California Department of Health Services, USA. dcowling@dhs.ca.gov
authors.forename: D W
authors.initials: DW
authors.lastname: Cowling
authors.forename: T P
authors.initials: TP
authors.lastname: Johnson
authors.forename: B C
authors.initials: BC
authors.lastname: Holbrook
authors.forename: R B
authors.initials: RB
authors.lastname: Warnecke
authors.forename: H
authors.initials: H
authors.lastname: Tang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002140:California / Q000453:epidemiology; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012044:Regression Analysis; D012650:Self Disclosure; D012907:Smoking / Q000453:epidemiology*; D011795:Surveys and Questionnaires