title: Comparison of bias resulting from two methods of self-reporting height and weight: a validation study.
abstract: OBJECTIVE
  To contrast the validity of two modes of self-reported height and weight data.
  
  
  METHODS
  Subjects' self-reported height and weight by mailed survey without expectation of subsequent measurement. Subjects were later offered a physical exam, where they self-reported their height and weight again, just prior to measurement. Regression equations to predict actual from self-reported body mass index (BMI) were fitted for both sets of self-reported values. Residual analyses assessed bias resulting from application of each regression equation to the alternative mode of self-report. Analyses were stratified by gender.
  
  
  METHODS
  Upstate New York.
  
  
  METHODS
  Subjects (n = 260) with survey, pre-exam and measured BMI.
  
  
  METHODS
  Prevalence of obesity based on two modes of self-report and also measured values. Bias resulting from misapplication of correction equations.
  
  
  RESULTS
  Accurate prediction of measured BMI was possible for both self-report modes for men (R (2 )= 0.89 survey, 0.85 pre-exam) and women (R (2 )= 0.92 survey, 0.97 pre-exam). Underreporting of BMI was greater for survey than pre-exam but only significantly so in women. Obesity prevalence was significantly underestimated by 10.9% (p < 0.001) and 14.9% (p < 0.001) for men and 5.4% (p = 0.007) and 11.2% (p < 0.001) for women, for pre-exam and survey, respectively. Residual analyses showed that significant bias results when a regression model derived from one mode of self-report is used to correct BMI values estimated from the alternative mode.
  
  
  CONCLUSIONS
  Both modes significantly underestimated obesity prevalence. Underestimation of actual BMI is greater for survey than pre-exam self-report for both genders, indicating that equations adjusting for self-report bias must be matched to the self-report mode.
authors: Bassett Healthcare Network Research Institute, One Atwell Road, Cooperstown, NY 13326, USA.
authors: Melissa
authors: M
authors: Scribani
authors: Bassett Healthcare Network Research Institute, One Atwell Road, Cooperstown, NY 13326, USA.
authors: Jessica
authors: J
authors: Shelton
authors: Bassett Healthcare Network Research Institute, One Atwell Road, Cooperstown, NY 13326, USA.
authors: David
authors: D
authors: Chapel
authors: Bassett Healthcare Network Research Institute, One Atwell Road, Cooperstown, NY 13326, USA.
authors: Nicole
authors: N
authors: Krupa
authors: Bassett Healthcare Network Research Institute, One Atwell Road, Cooperstown, NY 13326, USA.
authors: Lynae
authors: L
authors: Wyckoff
authors: Bassett Healthcare Network Research Institute, One Atwell Road, Cooperstown, NY 13326, USA.
authors: Paul
authors: P
authors: Jenkins
keywords: epidemiology; obesity; public health; research methods