The accuracy of self-reports is examined by measuring how closely they agree with actual measurements, where these are available. Previous research has suggested that there are differences between self-reports and measurements of weight. Nevertheless, empirical findings are inconclusive, and the determinants of misreporting have been examined in isolation. The study aimed to investigate the differences between self-reports and actual measurements of weight, whether gender, weight status, and age were related to these differences, and if weight reporting accuracy changed after frequent measurements of weight. Using a representative sample of Dutch individuals from the Longitudinal Internet Studies for the Social Sciences Panel, the study supported that on average participants underestimated their weight. No significant gender differences were found. Individuals with higher body mass index (BMI) underestimated their weight more than those with lower BMI, and the underestimation of weight was larger as individuals got older. Participants were more accurate reporters of their weight after frequent weighing. The findings of the study suggest that individuals underreport their weight in self-reports in systematic ways in this population. Researchers should consider collecting direct measurements to have reliable results or instruct respondents to weigh themselves before they are invited to report it.
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