From the Annals Of Really Bad Science Journal


This is simply terrible:

Imposing a minimum unit price for alcohol leads to a dramatic fall in drink-related crime, including murders, sexual assaults and drink-driving, a new study shows.

Crimes perpetrated against people, including violent assaults, fell by 9.17% when the price of alcohol was increased by 10% over nine years in the Canadian province of British Columbia. Motoring offences linked to alcohol, such as killing or injuring someone with a vehicle and refusing to take a breath test, fell even more – by 18.8% – the study found.

An interesting finding but how good is the science?

Method: A time-series cross-sectional panel study was conducted using mixed model regression analysis to explore associations between minimum alcohol prices, densities of liquor outlets, and crime outcomes across 89 local health areas of British Columbia between 2002 and 2010. Archival data on minimum alcohol prices, per capita alcohol outlet densities, and ecological demographic characteristics were related to measures of crimes against persons, alcohol-related traffic violations, and non–alcohol-related traffic violations. Analyses were adjusted for temporal and regional autocorrelation.

Results: A 10% increase in provincial minimum alcohol prices was associated with an 18.81% (95% CI: ±17.99%, p < .05) reduction in alcohol-related traffic violations, a 9.17% (95% CI: ±5.95%, p < .01) reduction in crimes against persons, and a 9.39% (95% CI: ±3.80%, p .05). Densities of private liquor stores were not significantly associated with alcohol-involved traffic violations or crimes against persons, though they were with non–alcohol-related traffic violations.

So, they examined minimum alcohol prices and traffic violations in British Columbia. What did they not measure? Changes in traffic violations in Canadian society in general. In, perhaps, areas that did not have the rise in minimum pricing.

For all the ordure that it thrown at economists and their models these days at least this would never be published in an economics journal. Because the first reviewer, heck, even the editor pondering whether to send it out for review, would first ask, well, what was that general change so that we can measure the effects of this specific change against it?

Not that we're about to do that detailed analysis, we'll leave that to the excellent Chris Snowdon over at the IEA. But an indication from Canada's 2010 crime statistics:

In 2010, police reported about 84,400 incidents of impaired driving (Table 4). The number of impaired driving offences reported by police can be influenced by many factors including legislative changes, enforcement practices (e.g. increased use of roadside checks) and changing attitudes on drinking and driving.

The 2010 rate of impaired driving was down 6% from the previous year, representing the first decrease in this offence since 2006 (Chart 14). The rate of impaired driving has been generally declining since peaking in 1981.

No, we don't know but we've got at least a definite impression. Booze related driving incidents have been declining in general for 30 years. To the point that in the final year alone of this paper's measurements they actually declined nationwide by 6%. And they're trying to pin an 18% decline over a decade on a minimum price change that only happened in one province?

And they don't compare the declines in that one province with other provinces?

This might be all sorts of things but it ain't science, is it?