@Article{info:doi/10.2196/jmir.2393,
author="Bonn, Stephanie Erika
and Trolle Lagerros, Ylva
and B{\"a}lter, Katarina",
title="How Valid are Web-Based Self-Reports of Weight?",
journal="J Med Internet Res",
year="2013",
month="Apr",
day="09",
volume="15",
number="4",
pages="e52",
keywords="body weight; Internet; validity",
abstract="Background: Many studies rely on self-reported anthropometric data. While paper-based self-reports have been the standard collection mode, the number of studies collecting self-reported data via the Web is increasing rapidly. Although numerous studies have shown good agreement between self-reported and measured weight using paper-based questionnaires, the validity of using the Web to inquire about weight is unknown. Objective: The objective of this study was to validate Web-based self-reports of bodyweight compared to weight measured at the study center. Methods: The validity of weight self-reported via the Web was assessed by comparing self-reports against measurements of weight in a convenience sample of 149 individuals (77.2{\%} women, 115/149), aged 20-65 years. Study participants self-reported their weight via a Web-based questionnaire and thereafter had their weight measured in the research center. Results: The Spearman correlation coefficient between self-reported and measured weight was 0.98 (P<.001). The mean difference between self-reported and measured weight was -1.2 (SD 2.6) kg. There was a statistically significant difference between self-reported and measured weight with the self-reported being lower (P<.001). Subjects with a body mass index (BMI) ≥25 kg/m2, and subjects ≥30 years of age, under-reported their weight statistically significantly more than subjects with a BMI <25 kg/m2, and subjects <30 years of age, respectively. Conclusions: Our results show that self-reported weight via the Web can be a valid method of data collection. ",
issn="1438-8871",
doi="10.2196/jmir.2393",
url="http://www.jmir.org/2013/4/e52/",
url="https://doi.org/10.2196/jmir.2393",
url="http://www.ncbi.nlm.nih.gov/pubmed/23570956"
}