Drinking statistics misrepresented - again

Three newspapers reported on Friday (April 1) that a fifth of women were drinking too much, and that the numbers exceeding the 14 units a week recommended level had grown by a fifth in a decade.
It wasn't an April Fool. The source of the story was the Office for National Statistics, which ought to have known better. In a report on NHS productivity, various changes were cited which might have contributed to an increased demand for healthcare. One was alcohol. “The percentage of females consuming more than the weekly recommended units of alcohol has increased by a fifth since 1998” it said.
This sentence was included in the press release and picked up by The Daily Telegraph, the Daily Mail and the Daily Star. But it is wrong.
The source of the data is the General Lifestyle Survey, 2009. Table 2.2 is a time series for those drinking more than the recommended limits. I have extracted data for 1998 to 2009 (see Table).

This shows a slow decline from 1998 to 2006, followed by an abrupt increase which was caused by a change in methodology. The percentage of women exceeding the limit surged from 12 to 20 per cent when this new method for converting volumes of alcohol to units was applied. Since then the slow decline has resumed.
There is no evidence here that actual drinking habits have changed. It is possible the old method underestimated drinking before 2006, and the new one is better. But this data is not evidence of a rising trend: the surprise is that the author of the ONS report did not realise this.
Nor is it true, as the Daily Mail asserts, that recent figures have pointed to a surge in binge drinking among females, particularly young girls. The percentage of 16-24 year-olds who drank more than three units on any one day has declined since 1998 from 42 per cent to 37 per cent, and the percentage who drank more than six units on at least one day has barely increased, from 23 to 25 per cent.
This is before taking account of the change in methodology, which itself added five percentage points to the score. Not much evidence here of a surge in binge drinking among young women. Perhaps the Mail meant an even yoiung age group than this, but if so it is not clear where the data originated.
The Portman Group, the industry-funded group that champions sensible drinking, wrote to the Mail pointing out the error, but the letter hasn’t so far been published.