Estimates of rates of problem gambling in Britain primarily come from three British Gambling Prevalence Surveys published by the Gambling Commission in 1999, 2007 and 2010. Each report uses two slightly different methodologies and found the following:

In 1999, it was estimated that 0.6% of the adult population were problem gamblers under the DSM methodology, with a confidence interval of 0.4-0.8%. Under the alternative measure of the South Oaks Gambling Scheme (SOGS), problem gambling prevalence was estimated to be slightly higher: 0.8% with a confidence interval of 0.6-1.0%.

The second British Gambling Prevalence Survey (2007) found similar rates: 0.6% under the DSM methodology (with a confidence interval of 0.5-0.8%) and 0.5% under the PGSI methodology (with a confidence interval of 0.4-0.8%).

The third and, as it transpired, final British Gambling Prevalence Survey in 2010 found a problem gambling prevalence of 0.9% under the DSM methodology with a confidence interval of 0.7-1.2%. Under the PGSI methodology, problem gambling prevalence was 0.7% with a confidence interval of 0.5-1.0%.

None of these figures differ greatly from the others. The confidence intervals are quite wide because problem gambling is relatively rare. The 2010 survey, for example, questioned 7,756 people but found only 64 problem gamblers. We must be wary of drawing firm conclusions on the basis of a handful of people and the authors of the British Gambling Prevalence Survey are right to refuse to pin problem gambling rates down to a tenth of one per cent. There is a 95% chance that the true figure falls somewhere within the confidence interval, but the researchers can be certain about little more than that.

Unfortunately, anti-gambling campaigners and the media are less respectful of statistical probity. Campaigners against fixed odds betting terminals have claimed that “problem gambling in the UK has increased by 50% in three years”—an assertion that is based on comparing the mid-point estimates from 2007 and 2010 under the DSM methodology. In fact, all of the figures reported in the three British Gambling Prevalence Surveys are consistent with Britain having a problem gambling prevalence of around 0.7%, which is low to middling by international standards.

Responsibility for collating problem gambling data has since been moved to public health departments in England, Scotland and Wales. The first of the new figures were published today in the Scottish Health Survey and they indicate that there has been no rise in problem gambling since 1999. Under both the DSM and PGSI methodologies, problem gambling prevalence in Scotland was found to be 0.7%, with similar confidence intervals of 0.5-1.1% and 0.5-1.2%.

The report notes that these figures are in line with previous surveys:

These 2012 estimates are similar to those observed for Scotland in the BGPS 2010, which estimated that 1.1% (DSM-IV) and 0.9% (PGSI) adults in Scotland were problem gamblers. The confidence intervals around the BGPS estimates were large due to small bases sizes for Scotland. The 95% confidence interval for the BGPS DSM-IV estimate was 0.4% – 2.8% and for the PGSI was 0.4% – 2.2%. This meant that we were 95% confident that the true estimate fell between these figures. The figures produced for the Scottish Health Survey in 2012 (0.7%) are well within this range and are not statistically different from the BGPS estimates.

If we used the campaigners’ trick of looking only at the mid-point estimates, we could say that problem gambling has fallen by 40% in Scotland since 2010. That would be highly disingenuous, of course. We can only say that seven years after the last Labour government relaxed Britain’s gambling laws—and twelve years after fixed odds betting terminals were introduced to betting shops—there is still no evidence of a rise in problem gambling prevalence.