Puzzling statistics on drinking in Scottish schoolchildren

The Scotsman headlines its report today on new statistics on alcohol consumption in Scottish schoolchildren “One in seven children ‘drinking regularly’”.

That’s not what the report actually says, or the statistic show. The report correctly identifies that one in seven 13 year-olds (14.8 per cent of boys, 13.6 per cent of girls) told the survey that they drank alcohol “last week”. But only 5.6 per cent of boys and 5.4 per cent of girls this age said they drank at least once a week - that is, regularly.

Among 15 year-olds the figures are much higher – more than a third drank “last week” and around one in five once a week.

There’s no reason to doubt the figures, as this is a big and well-conducted study, The Scottish Schools Adolescent Lifestyle and Substance Use Survey. But there is something puzzling about them. While most of the tables show a decline in drinking, the “last week” tables show an increase.

For example, the number of 13 year-olds drinking at least once a week has fallen from 8.4 per cent of boys and 8.1 per cent of girls in 2008 to 5.6 and 5.4 per cent respectively in 2010. The number of 13 year-olds who have ever had an alcoholic drink alcohol has also fallen, from 52 per cent in 2008 to 44 per cent in 2010. The same trends apply, though less strongly, to 15 year-olds.

Yet the proportion drinking “last week” has risen, and quite sharply: from 10.7 per cent of 13 year-old boys in 2008 to 14.8 per cent in 2010 and by smaller but still significant amounts among 13 year-old girls and 15 year-olds of both sexes.

If true, it means that “last week” drinking among 13 year-old boys in Scotland has risen by 38 per cent over the same period as it has fallen by 40 per cent in the same age group in England. Among 15 year-old boys the rise in Scotland is 9.6 per cent, while the fall in England is 23.7 per cent. It sounds unlikely.

There may be a clue in the cautions the authors of the Scottish statistics raise about year-on-year comparisons. Compared with the 2008 survey, the 2010 sample had fewer 12 year-olds and more 15 year-olds because a higher proportion of forms were not completed until late in the survey period. Propensity to drink rises rapidly with age, so a slightly older sample might account for some of the increase. The 2002 and 2004 cohorts were older still as a result of a later fieldwork period, and those years also reported high “last week” figures.

It will be interesting to see if the 2012 data show a continuing rise. Long time to wait, though.