title: The obesity epidemic and changes in self-report biases in BMI.
abstract: OBJECTIVE
  To assess time trends in measurement error of BMI and the sensitivity/specificity of classifying weight status in the United States by analyzing the difference in BMI between self-reported and measured height and weight.
  
  
  METHODS
  Data from 18,394 respondents aged 20-89 years from the National Health and Nutrition Examination Survey (NHANES) from 1999 through 2008 were analyzed. Multiple linear regression and logistic regression models estimated trends in reporting bias and misclassification of weight status by BMI categories, sex, age, and racial/ethnic groups, adjusting for the sampling design.
  
  
  RESULTS
  We find no evidence that there are time trends in the accuracy of self-report by BMI categories, sex, age, or racial/ethnic groups. The well-known downward bias in self-report has remained stable over the last decade; approximately one in six to seven obese individuals were misclassified as nonobese due to underestimation of BMI.
  
  
  CONCLUSIONS
  Increases in obesity rates based on self-reported height and weight are likely to reflect actual weight increases and are not inflated by changes in reporting accuracy.
authors.affiliation: Carolina Population Center, University of North Carolina at Chapel Hill, CB# 8120, Chapel Hill, NC 27516-2524, USA. hattori@email.unc.edu
authors.forename: Aiko
authors.initials: A
authors.lastname: Hattori
authors.forename: Roland
authors.initials: R
authors.lastname: Sturm
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015982:Bias; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D005006:Ethnicity; D005260:Female; D006801:Humans; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D009765:Obesity / Q000453:epidemiology*; D057566:Self Report; D012680:Sensitivity and Specificity; D014481:United States / Q000453:epidemiology; D055815:Young Adult