Original article Two-Method Measurement for Adolescent Obesity Epidemiology: Reducing the Bias in Self-Report of Height and Weight Keith M. Drake, Ph.D. a, * , Meghan R. Longacre, Ph.D. a, b , Madeline A. Dalton, Ph.D. a, b, c , Gail Langeloh, M.S. a , Karen E. Peterson, D.Sc. d, e , Linda J. Titus, Ph.D., M.A. a, b, c , and Michael L. Beach, M.D., Ph.D. a, c, f a Hood Center for Children and Families, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire b Department of Pediatrics, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire c Department of Community and Family Medicine, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire d Human Nutrition Program, School of Public Health, University of Michigan, Ann Arbor, Michigan e Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts f Department of Anesthesiology, DartmoutheHitchcock Medical Center, Lebanon, New Hampshire Article history: Received October 26, 2012; Accepted March 25, 2013 Keywords: Statistical methods; Body mass index; Obesity; Height and weight measurement; Epidemiology A B S T R A C T Background: Despite validation studies demonstrating substantial bias, epidemiologic studies typically use self-reported height and weight as primary measures of body mass index because of feasibility and resource limitations. Purpose: To demonstrate a method for calculating accurate and precise estimates that use body mass index when objectively measuring height and weight in a full sample is not feasible. Methods: As part of a longitudinal study of adolescent health,1,840 adolescents (ages 12e18) self- reported their height and weight during telephone surveys. Height and weight was measured for 407 of these adolescents. Sex-specific, age-adjusted obesity status was calculated from self-reported and from measured height and weight. Prevalence and predictors of obesity were estimated using self-reported data, measured data, and multiple imputation (of measured data). Results: Among adolescents with self-reported and measured data, the obesity prevalence was lower when using self-report compared with actual measurements (p < .001). The obesity prevalence from multiple imputation (20%) was much closer to estimates based solely on measured data (20%) compared with estimates based solely on self-reported data (12%), indicating improved accuracy. In multivariate models, estimates of predictors of obesity were more accurate and approximately as precise (similar confidence intervals) as estimates based solely on self-reported data. Conclusions: The two-method measurement design offers researchers a technique to reduce the bias typically inherent in self-reported height and weight without needing to collect measure- ments on the full sample. This technique enhances the ability to detect real, statistically significant differences, while minimizing the need for additional resources. Ó 2013 Society for Adolescent Health and Medicine. All rights reserved. IMPLICATIONS AND CONTRIBUTION BMI based on self-reported height and weight is typically underestimated by adolescents. The two-method measurement design offers a strategy for improving BMI estimates in studies primarily relying on self-reported height and weight data when resources for collecting measured data in a full cohort are unavailable. Despite well-recognized limitations [1e 10], large epidemio- logic studies of adolescent health commonly use body mass index (BMI) based on self-reported height and weight as a primary measure of body fat because of feasibility and resource limitations. Compared with objective measures, self-reported height and weight can underestimate obesity prevalence among adolescents by 1.6% to 11.1% [1e4]. In general, girls and overweight or obese adolescents self-report heights and weights * Address correspondence to: Keith M. Drake, Ph.D., Hood Center for Children and Families, Geisel School of Medicine at Dartmouth, One Medical Center Drive, HB 7465, Lebanon, NH 03756. E-mail address: Keith.M.Drake@Dartmouth.edu (K.M. Drake). www.jahonline.org 1054-139X/$ e see front matter Ó 2013 Society for Adolescent Health and Medicine. All rights reserved. http://dx.doi.org/10.1016/j.jadohealth.2013.03.026 Journal of Adolescent Health 53 (2013) 322e327