Summary of key findings
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Obesity estimates for children based on parent-reported versus direct measures
Publication: Health Reports 2011:22(3) www.statcan.gc.ca/healthreports
Authors: Margot Shields, Sarah Connor Gorber, Ian Janssen and Mark S. Tremblay
Data: The 2007 to 2009 Canadian Health Measures Survey
The 2007 to 2009 Canadian Health Measures Survey (CHMS) collected both parent-reported and measured height and weight for a nationally representative sample of children aged 6 to 11. Using these data, this study investigates the bias that exists when height, weight and BMI are based on parent-reported values.On average, parents underestimated the height (3.3 cm) and weight (1.1 kg) of their children. Estimates of the prevalence of obesity were significantly higher when based on parent-reported versus measured values for children aged 6 to 8; the two collection methods yielded similar estimates of obesity for children aged 9 to 11. For children in both age groups, misclassification errors for BMI categories were substantial when based on parent-reported values. This weakened associations between obesity and health indicators such as aerobic fitness and systolic blood pressure. The variance explained by factors associated with the bias in parent-reported height and weight was small, particularly for height. The use of correction equations based on variables associated with the bias resulted in a very modest reduction in misclassification errors.
For more information about this article, contact Margot Shields (1-613-951-4177; Margot.Shields@statcan.gc.ca),Health Analysis Division, Statistics Canada.
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