English children fat, but no fatter
English children aren’t getting any thinner – but neither are they getting any fatter. That’s the message from the latest results from the National Child Measurement Programme.
The key to understanding the report is participation. When the NCMP was launched in 2005-06 , many parents chose to opt out, so their children weren’t measured or weighed. These tended to be the fatter kids.
Since then participation rates have increased year by year, to a pretty respectable 90 per cent in 2008-09. The Information Centre, who released today’s report, reckon that for every extra 10 per cent of pupils weighed and measured at the age of 11, obesity prevalence will rise by 0.6 percentage points (+/– 0.3 percentage points).
So some or all of the small rise recorded over the past three years in 11 year-olds can be attributed to higher participation. Five year-olds don’t seem to show the same effect. Working backwards, this means that the obesity rate in 11 year-olds in 2006-07 was underestimated by 1.3 percentage points, in 2007-08 by 0.8 percentage points, and in the latest figures, 2009-09, by 0.7 percentage points.
The effect of these corrections is to suggest that trends in 11 year-olds are flat: no increase, no decrease. Maybe now participation has reached a high level, we’ll begin to see a decline in the figures.
The other significant fact to glean from the figures is that they confirm very nicely the Health Survey for England data, which come from a much smaller sample. The 2006-07 figures have been compared and, apart from obese boys at age five where the HSE figure is higher, show no statistically significant differences. A comparison for 2007-08 is imminent.
This prompts the question: “was your NCMP really necessary?” If you can get the same results from a sample, why go to the expense and trouble of weighing and measuring them all? Maybe that’s a frivolous point – more seriously, if the close agreement between the two methods persists in future years it will provide a longer run of validated data which could be helpful in establishing trends.
Anonymous (not verified) wrote,
Fri, 16/04/2010 - 13:36
Just came across this and it is something I have argued working in a Primary Care Trust.
You are right to ask whether the NCMP is a waste of a time and resources at a national level, but it is very much of use at a local level as the HSE doesn't have a large enough sample to be published at a PCT level.