Questions on self-reported height and weight were added to the Active People Survey (APS) for the first time from January 2012 to provide data for monitoring excess weight in adults at local authority level for the Public Health Outcomes Framework (PHOF).
It is known that adults tend to underestimate their weight and overestimate their height when providing self-reported measurements and the amount to which this occurs can differ between population groups. Therefore prevalence of obesity and excess weight (overweight including obese) calculated from self-reported data is likely to produce lower estimates than prevalence calculated from measured data.
To assess the accuracy of the self-reported height and weight, data from the APS were compared with measured height and weight data from the Health Survey for England (HSE) 2006-2010. Similar analysis was performed using the 2011 HSE data where both self-report and measured height and weight were collected from the same individuals. These analyses found that the differences between self-reported and measured height and weight vary in a systematic way, primarily as a function of age and sex. This systematic variation can be described by formulas, which have been used to adjust self-reported height and weight measurements at an individual level to estimate the likely actual height and weight of those individuals.
The self-reported height and weight values for individuals have been multiplied by the appropriate adjustment factor for that age and sex to obtain an estimate of the true height and weight of that individual. Whilst these will not be precise at an individual level, at a population level they act to bring the APS data much more closely into line with the actual measures, such as those described by the HSE.
The counts were weighted to be representative of the whole population at each level of geography.
95% confidence interval upper limit and lower limit respectively. These figures give the range within which the true value of the sample estimate will lie 19 times out of 20.
Frequency: As Shown by DataSet