Nikolaos Tsigilis1. 1. Department of Physical Education and Sports, University of Thessaly, Greece. tsigilis@uom.gr
Abstract
BACKGROUND: Self-reported measures of height and weight are a cost-effective alternative to direct measures in large-scale studies. This study was designed to examine the accuracy of adolescent students' self-reported height and weight taking into consideration the magnitude of the differences. METHODS: Self-reported height and weight were taken from 300 secondary public schools students. Participants' actual height and weight were subsequently verified. Body mass index (BMI; kg/m2) was calculated separately from reported and from actual measures. Adolescents' whose measured BMI was above the 85th percentile were characterized as 'at risk for overweight/obese'. RESULTS: There was no gender effect on the discrepancy between reported and actual measures. Overall adolescents significantly underestimated their weight and BMI. Although correlation coefficients were high, eta-square (eta2) values indicate large bias for weight (0.36) and BMI (0.31). 'At risk for overweight/obese' individuals underestimated their weight and BMI to a greater extent than their 'normal weight' counterparts. CONCLUSIONS: The magnitude of the discrepancies call into question the accuracy of self-reported weight and consequently the estimated BMI. Correlation coefficients did not provide any valuable information about the discrepancy between the self-reported and actual measures. A better understanding of the validity of self-reported height and weight could be reached if interpretation of the results is based on both statistical significance and magnitude of the differences.
BACKGROUND: Self-reported measures of height and weight are a cost-effective alternative to direct measures in large-scale studies. This study was designed to examine the accuracy of adolescent students' self-reported height and weight taking into consideration the magnitude of the differences. METHODS: Self-reported height and weight were taken from 300 secondary public schools students. Participants' actual height and weight were subsequently verified. Body mass index (BMI; kg/m2) was calculated separately from reported and from actual measures. Adolescents' whose measured BMI was above the 85th percentile were characterized as 'at risk for overweight/obese'. RESULTS: There was no gender effect on the discrepancy between reported and actual measures. Overall adolescents significantly underestimated their weight and BMI. Although correlation coefficients were high, eta-square (eta2) values indicate large bias for weight (0.36) and BMI (0.31). 'At risk for overweight/obese' individuals underestimated their weight and BMI to a greater extent than their 'normal weight' counterparts. CONCLUSIONS: The magnitude of the discrepancies call into question the accuracy of self-reported weight and consequently the estimated BMI. Correlation coefficients did not provide any valuable information about the discrepancy between the self-reported and actual measures. A better understanding of the validity of self-reported height and weight could be reached if interpretation of the results is based on both statistical significance and magnitude of the differences.
Authors: Brook E Harmon; Claudio R Nigg; Camonia Long; Katie Amato; Mahabub-Ul Anwar; Eve Kutchman; Peter Anthamatten; Raymond C Browning; Lois Brink; James O Hill Journal: Psychol Sport Exerc Date: 2014-05-01
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