Saturday 25 August 2012

Alcohol stats

I wrote this for the op-ed section of Friday's Christchurch Press. I'm currently in Oz where I'll be talking about alcohol policy for the hospitality industry association liquor retailers conference and with a few journalists. So I'm posting this Wednesday and hoping that the piece did come out in Christchurch on Friday. Anyway, enjoy. [Update: here it is!]


It would be pretty easy for diligent Christchurch Press readers to conclude that alcohol is the worst scourge of humanity. Doug Sellman featured several times over the last fortnight warning us all of alcohol’s dangers; health reporter Georgina Stylianou wrote two articles on a new estimate of alcohol’s cost to the Canterbury health budget. And the University of Otago’s Professor Jennie Connor told us that minimum prices are remarkably effective in reducing alcohol consumption, pointing to a Canadian study “that showed a 10 per cent increase in the minimum price of alcohol reduced consumption by 16 per cent relative to other drinks.” Connor was quoted in a Mainlander feature on Doug Sellman explaining how Professor Sellman is not in fact a wowser; presumably it’s only free-spirited libertines who write op-eds in the New Zealand Herald worrying about how Woodstock commercials encourage boys “to have sex with their best mates’ mothers” and that advertisements “encouraging middle-aged women to get their teenage clothes back on and flirt with their son’s best mates” do not contribute to a healthy society.  (30 October 2009)

I do not particularly care what the jury decides on who is or is not a wowser. But I work with and care about the numbers around alcohol policy. And the impression most readers would get from the latest reporting in the Press is a bit at odds with, well, reality.

Let us begin perhaps with Jennie Connor’s citing of “a Canadian study” on the effects of minimum pricing. Can a ten percent increase in the minimum price of alcohol really reduce total alcohol consumption by sixteen percent? No. The number is so far out of line with the vast consensusof the literature that I got in touch with Chris Auld, one of the authors of what had to have been the study Connor had read, a piece in the May 2012 issue of Addiction. And my read of his study was right. If you increase the price of beer by ten percent, you could get a reduction in beer consumption of sixteen percent, but that’s because beer drinkers move over to other alcoholic drinks. Across-the-board increases in the minimum price of alcohol have far smaller effects: a ten percent price increase reduces aggregate consumption by only about 3.4 percent, as is made reasonably clear in Auld’s paper.

That the sixteen percent figure is screamingly wrong should have been obvious to anybody who is familiar with the literature. The largest estimate of the responsiveness of alcohol consumption to price measures in Wagenaar’s 2009 survey of 112 different studies suggested that a 10% price hike reduced consumption by 8.4%; Wagenaar concluded that 4.4% is the best consensus estimate. And for heavy drinkers, it was 2.8%. Auld’s 3.4% is then right where a reasonable person would have expected an estimate on the effects of minimum prices might fall. Sixteen percent – that’s right out.

The Auld study does come out in favour of minimum prices, but in conjunction with a decrease in alcohol excise taxes: it’s then a way of increasing the cost facing heavier drinkers while doing less harm to moderate drinkers if heavier drinkers drink cheaper alcohol. I worry more that the policy does disproportionate harm to moderate-drinking poorer people.

I was a bit more surprised to read of the new commissioned BERL report on the health costs of alcohol in Canterbury. Their prior work in the field, a 2009 study that included a measure of costs to the health system among other costs of alcohol, seemed to put a pretty heavy thumb on the scales in estimating the costs borne by the health system. My article in today’s issue of the New Zealand Medical Journal lists a few of those problems [note: link may only be active after lunchtime Friday, sorry]. While alcohol greatly increases the burden of disorders like liver cirrhosis, it also reduces the costs of cardiovascular disease. BERL here replicated work done in Australia by Collins and Lapsley (2008). But where Collins and Lapsley added up all the costs imposed by those disorders where alcohol makes things worse and subtracted from that total all the cost savings from those disorders where alcohol reduces costs, BERL simply erased any beneficial effects of alcohol for disorders including ischaemic heart disease, cholelithiasis, heart failure, stroke and hypertension.

As I had warned BERL against this kind of method when I served as discussant on their paper at the 2009 New Zealand Economic Association Meetings, I was curious whether they’d revised things. But, the new BERL paper wasn’t available. Two separate stories in the Christchurch Press, with lots of reaction quotes from doctors, were based on a paper that the reporter did not have and was not yet available for public critique. I received the paper Wednesday courtesy of the CDHB. And BERL, at footnote 14, reports they’ve done the same thing again: “The Collins and Lapsley fractions indicate some alcohol use may be beneficial for some conditions. We concentrate on harmful drug use, and assume zero fractions for such conditions.” So their measure of the costs of alcohol to the Canterbury health system relies on an assumption that there can be no health benefits from alcohol – an assumption that runs contrary to the weight of international evidence. Assuming one’s conclusions is hardly proper method.

Unfortunately, alcohol policy is one of those areas where a lot of people’s convictions about the right answer put a pretty strong lens on how they assess the literature. How often do you read that problem drinking among 15-24 year olds was no different in 2006/2007 than in 1996/1997 before the change in the alcohol purchase age? Or that per capita alcohol consumption is down substantially since 1991? Or that light drinkers have about a 14% reduction in their chance of dying from any cause than people who never drink,correcting for the host of other health-related behaviours that are usually given as reasons for ignoring the health benefits of moderate drinking?

Be skeptical of the moral crisis around alcohol.


  1. Standard economic models cannot predict crises like that observed in 2008-09. Yes and No! They cannot predict when it is going to happen, but just that we know it will eventually happen. If you toss 1-dye, cannot predict the outcome. But if you toss a dye 1-million times and sum the outcome, then the prediction is 3.5 million which will be very close to the actual number. Economists have two problems: They do not take into account the importance or random events, which by their definition cannot be predicted; and second they confuse predicting equilibrium with predicting the path to equilibrium. As noted by Keynes, even he could not accomplish the latter.

    The Financial Historial

  2. Comments at the Press hold out little hope for a future NZ of citizens who can actually think unfortunately ...