title: Evidence of telescoping in regular smoking onset age.
abstract: BACKGROUND
  We examined the evidence of telescoping bias in self-reports of regular smoking onset age. Since the exact year of the onset was not available, the discrepancy (termed shift) in self-reports was explored. The study was targeted at establishing the relationships between the prevalence and the magnitude of shifting and respondent and survey characteristics and identifying the key factors contributing to forward and backward shifting.
  
  
  METHODS
  The 2002-2003 Tobacco Use Supplement to the Current Population Survey was administered using phone and in-person interviews to the same respondents in 2002 and 2003. The regular smoking onset age, reported by current and former smokers during both years, was used. All statistical analyses incorporated replicate weights to adjust for the complex survey design.
  
  
  RESULTS
  In our sample, about 31.6% (31.8%) of respondents forwardly (backwardly) shifted the smoking onset age, with the mean magnitude of discrepancy about 2.7 years (both directions). The elapsed time since the onset was shown to be the most important considered predictor of prevalence of shifting. The prevalence of forward (backward) shifting tends to increase (decrease) as elapsed time increases. Furthermore, the discrepancy in forwardly shifted responses tends to increase, on average, with elapsed time.
  
  
  CONCLUSIONS
  The findings indicate that both forward and backward shifting may be prevalent in reports on smoking onset age. The extent of shifting depends on elapsed time since the onset (and therefore, the respondent's age) and other respondent and survey characteristics. The findings are consistent with presence of both forward and backward telescoping biases.
authors.affiliation: Department of Statistics, University of Nebraska-Lincoln, Lincoln, NE.
authors.forename: Brianna C
authors.initials: BC
authors.lastname: Bright
authors.forename: Julia N
authors.initials: JN
authors.lastname: Soulakova
mesh_terms: D000293:Adolescent; D017668:Age of Onset; D015982:Bias; D003625:Data Collection; D003710:Demography; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D057566:Self Report; D012907:Smoking / Q000453:epidemiology*