Data?

I'm curious where Jennie Connor's gotten her numbers for this one:

University of Otago Preventive and Social Medicine head Prof Jennie Connor, who is the chairwoman of a university group set up to tackle problem drinking, said students were drinking more heavily than they did 10 years ago.

''In the last 10 years, there has been an increase in how much they drink and the frequency of heavy episodes of drinking.''

''A larger proportion of all students drink and drink heavily. Not just at Otago but at all universities, and probably in the general population of young people,'' she said.

The main driver of the change in drinking culture was the introduction of wine and beer sales in supermarkets and the lowering of the purchase age from 20 to 18.

''A whole new drinking culture has grown up around heavy drinking outside of a pub environment,'' he said.

She was not quite so enthusiastic about getting more students to drink in pubs, but accepted there were more ''social aspects'' that came with that.

''There is no evidence that drinking in pubs is safer, and most assaults that happen outside the home happen near pubs - the violence is usually outside rather than inside, when intoxicated people who don't know each other mix together. 'Supervision' by pub staff is usually minimal at best,'' she said. [emphasis added above]

I have no data on drinking by students at Otago, and it's very likely that Jennie would have that kind of data if it existed. But she's asserting that a larger proportion of students, and likely of young people in general, are drinking and are drinking heavily. And I do know the data on that one.

The MoH survey released a couple of months ago showed strong decreases in youth drinking. The survey said:

"The largest drop in past-year drinking was among youth aged 15-17, whose rate fell from 75% in 2006/07 to 59% in 2011/12."

Hazardous drinking dropped among youths who do drink. As fewer kids drink at all, the proportion of kids in total reporting hazardous drinking is well down. The trend from 1996/1997 through 2006/2007 was pretty flat, then dropped substantially through 2011/2012.

And Jennie knows about that survey. She was quoted on it when it came out. She said:

"I was quite alarmed by the results. In particular, in the age 18 to 24, one in four women are drinking in a hazardous fashion. And for the men, it's even higher - it's over 40 percent. So I think we should be very concerned about that."

She there didn't talk about the time trend, but the time trend was the big story in that survey. Here are the Selected Key Findings; I've bolded the relevant time-series youth-related ones.

Selected key findings

• In 2011/12, most adults had consumed alcohol in the past 12 months (80%). This is fewer than in 2006/07 (84%). Decreases in past-year drinking were generally seen across all age groups, but particularly among 15–17 year olds.
• Among people who had consumed alcohol in the past 12 months (‘past-year drinkers’), one in five (19%) had hazardous drinking patterns. This is about 532,000 people.
• Since 2006/07, the level of hazardous drinking among past-year drinkers has significantly decreased for men (from 30% to 26%), but not among women (13% to 12%).
• People aged 18–24 years (particularly men) are at higher risk of hazardous drinking. Among past-year drinkers, about 44% of men and 26% of women aged 18–24 years have hazardous drinking patterns. However, the rate of hazardous drinking has decreased significantly in past-year drinkers aged 18–24 years from 2006/07 (49%) to 2011/12 (36%).
• Māori have similar rates of past-year drinking as the total population, but have higher rates of hazardous drinking. Rates of hazardous drinking among Māori adults have decreased since 2006/07, (from 33% in 2006/07 to 29% in 2011/12).
• While Pacific adults are less likely to drink alcohol, those who do are more likely to have hazardous drinking patterns (35%) than adults overall (19%).
• People living in more deprived areas are less likely to have consumed alcohol in the past 12 months, but are more likely to have hazardous drinking patterns (18%), than people living in less deprived areas (11%).  

Perhaps Connor has a new survey that I've not heard about.

As for any links to the alcohol purchase age...

Our manufactured drinking crisis

Boy, they keep looking for dark linings to silver clouds, don't they?

Here's Jennie Connor on the latest findings from the Ministry of Health hazardous drinking survey. She says,

"I was quite alarmed by the results. In particular, in the age 18 to 24, one in four women are drinking in a hazardous fashion. And for the men, it's even higher - it's over 40 percent. So I think we should be very concerned about that."

So, what's so alarming? Let's look at the survey.

First, note that hazardous drinking patterns are defined as a score of 8 points or more on the 10-question Alcohol Use Disorders Identification Test. Here is an online version of the test. I score a six for having a glass of wine or beer with dinner every night, having seven or more standard drinks less than once per month, and for having a feeling of guilt or remorse after drinking* less than once per month. It isn't hard to score an 8; that's why so many people score an 8.

Now, what do the time trends look like? Here are the charts from the document.

Figure 1 shows us that the number of non-drinkers has increased since 2006/2007. Among adults, the proportion who consumed alcohol in the past year dropped from 84% to 80%. They note that the drop was larger in youth cohorts: "The largest drop in past-year drinking was among youth aged 15-17, whose rate fell from 75% in 2006/07 to 59% in 2011/12."

Recall that I've previously argued that there is no evidence of any crisis in youth drinking, that Steve Stillman has found the same thing using more rigorous method than my ocular least squares, and that the monster-shouters have shouted a lot about how we need to up the alcohol purchase age to 20. 

Now on to hazardous drinking. In all the tables below, you'll note that the rates are defined as a proportion of those who drink, not as a proportion of everybody. This matters when the proportion of non-drinkers is rising. If you're comparing 2011/2012 rates to 2006/2007, and you want to normalise to total population rather than to the population of drinkers, you have to multiply by 0.8 for 2011/2012 and by 0.84 for 2006/2007. In other words, the drop in hazardous drinking is even larger when we measure it as a fraction of the total population rather than as a fraction of all drinkers.

The Ministry of Health also is very clear that the tables above understate the drop in hazardous drinking if we're interested in it as a proportion of the overall population. They write:

Since 2006/07 the level of hazardous drinking among male past-year drinkers has fallen from 30% to 26%. Among female past-year drinkers, the level of hazardous drinking has not changed significantly between 2006/07 (13%) and 2011/12 (12%).

Among all adults (not just past-year drinkers), the rate of hazardous drinking fell significantly since 2006/07 for men (from 26% to 22%) and for women (from 11% to 9%).

When we break things down by age and gender, the highest rates are among young men.

But when we look at the trend, it's dropped substantially among 18-24 year olds since 2006/2007. And, again, this understates the true drop because the proportion of past-year drinkers has dropped.

And recall that there had been no increase in hazardous drinking among 15-24 year olds from 1996/1997 through 2006/2007. Our youth drinking crisis? Flat from 1996/1997 through 2006/2007, then a substantial drop.

If we look at income patterning, richer people are more likely to have consumed alcohol in the last year but, conditional on consuming alcohol, poorer cohorts are more likely to report hazardous drinking. Netting the two effects, MoH reports, "As a proportion of all adults, about 18% of those living in the most deprived areas and 11% of those in the least deprived areas had hazardous drinking patterns."

The cross-sections tell us where potentially problem drinking is currently concentrated. But the big picture really shows declines in potentially harmful drinking. If the anti-alcohol brigade had managed to get a purchase age increase in 2009, they'd be claiming these results as strong evidence of their success, while insisting that much more is still needed.

Why isn't the anti-alcohol lobby celebrating these results instead of saying how alarming they are? Do they somehow need for there to be a crisis?


* Note, it's after drinking, not because of drinking. I have a glass of wine or beer with dinner just about every night. Do you go a month without regret?

Ban the Cup

The latest research out of the University of Otago warns of the dangers of major sporting events.

It seems Rugby-World-Cup-related sex is dangerous. I can't access the original article as the journal is currently returning a 503 error code, so I'll have to rely on the newspaper reporting.

According to the New Zealand Herald, folks attending Sexual Health Clinics around the time of the Cup were surveyed. Those reporting having had RWC-related sex, about 7% of the sample, had higher risk of STDs, often reported having consumed alcohol before the act [the DomPost says 70% had consumed alcohol], and rarely reported having used condoms. From this, the authors argue for reduced promotion and availability of alcohol around future large sporting events.

Again, I haven't access to the article. But a few things come to mind.

First, sample selection is an awfully large problem here. 151 people attended a Sexual Health Clinic after having had RWC-related sex. How many people had sex after a fun night out watching the matches, didn't wind up with suspicious itches or discharges, and so didn't go to visit a Sexual Health Clinic? What was the rate of alcohol or condom use among those who failed to show up at a Sexual Health Clinic? How many of them simply had a great time without negative consequences? Recall that alcohol consumption correlates with positive sexual experiences.

A second sample-selection issue is that folks reporting RWC-related sex are probably really reporting "sex after hooking up at a RWC party or event", which won't be that different from "sex after hooking up at any party or event". And, in that case, again, is the fault with the alcohol, or is it that people going out and wanting to have a good time are more likely to drink and also more likely to think that hooking up is fun? Recall that the answer to "Do you like beer?" is a significant predictor of whether someone will have sex on the first date. The omitted underlying variable is then likely some combination of sensation-seeking, risk preference, and hedonism. Unless you control for that underlying heterogeneity, you're going to draw some awfully misleading conclusions from straight correlations among the various outcomes of that underlying agent-type.

Finally, here's how the Herald describes "RWC-related sex":

People who had RWC-related sex were defined as New Zealanders who had sex related to the RWC or other associated events, New Zealanders whose sexual event leading to the clinic visit was with an overseas visitor primarily in New Zealand for the RWC, and individuals visiting New Zealand primarily for the RWC.

So, basically then, people who report having hooked up with a tourist, tourists hooking up with locals, and folks hooking up at parties are more likely to engage in riskier sexual activities, many of them have had a few drinks, and some of them show up at Sexual Health Clinics. Policy conclusion: crack down on alcohol.

About 133,000 tourists showed up for the RWC; rather a few locals attended RWC events. 151 people showed up at Sexual Health Clinics afterwards. Suppose that ten percent of the tourists here for the RWC had some kind of RWC-related sex with locals, each only having one local partner. That's then about 26,500 people having had RWC-related sex; add to that locals hooking up with each other. I have no clue how close to right those estimates are. But I'd be pretty surprised if that 151 were more than 1% of the total RWC-related hook-ups. And this is the basis for an alcohol crackdown?

Otago remains an interesting place.

A hopefully concluding note on the price elasticity of alcohol

A condensed version of the letter I'd sent to the Press appeared in its letters section last week. My shortened letter:

In Monday's Press, Doug Sellman argued that differences in our interpretations of Chris Auld's study on the effects of minimum prices on consumption hinged on that the clause "relative to other drinks" was missing in one journalistic interpretation. This is hardly the case.

The Sellman press release said "A recent Canadian study has shown that a 10% increase in the minimum price of alcohol reduces its consumption by 16% relative to other drinks." As this statement was interposed between sentences noting the effectiveness of minimum prices in reducing consumption of alcoholic beverages, the reader could be forgiven for drawing the conclusion that the study Sellman cites finds that large a reduction in consumption of alcoholic beverages relative to non-alcoholic beverages. However, "other drinks" here did not mean that.
The sixteen percent estimate instead tells us what happens to, for example, beer consumption when the price of beer increases substantially and consumers then instead consume wine. It is highly misleading to present this as the expected effect of an across-the-board increase in prices.

It is especially misleading when the cited study did provide an estimate of the effects of minimum prices: a minimum price that lifts all prices by ten percent would decrease aggregate consumption of alcoholic drinks by only 3.4%. Indeed, Chris Auld, the economist responsible for the empirical analysis in the work cited by Sellman and Connor, writes in comment on my blog, and subsequently confirmed by email: "Eric, for the record, I agree with your interpretation, and I think Sellman and Connor's wording is very misleading." 

Doug Sellman and Jennie Connor's reply in Monday's paper this week:

"Dr Crampton continues his attack on us and does not admit that he made a mistake in quoting from an incorrect secondary source (Sept 11). But he does downgrade the charge from "screamingly wrong" to "very misleading", and if he were to take several more deep breaths he would realize we are essentially in agreement. We have said often over the past three years that there is no magic bullet to change the heavy drinking culture and the harm that results from it.

Although raising the price is probably the most effective and easily enacted measure the Government could put in place, it is not going to achieve the degree of change that is needed on its own.

However, the fact that a 10 per cent rise in minimum price results in a 3.4 per cent decrease in aggregate consumption should not be dismissed as trivial.

A reinforcing set of alcohol reforms, involving marketing, accessibility, purchase age and drink driving, in addition to raising alcohol prices, is likely to be required to bring about substantial change to the out-of-control and damaging state of alcohol use in New Zealand."

I continue to fail to see how there is any relevance in whether one includes "compared to other drinks". If they'd said "compared to other alcoholic drinks", then I'd have been perpetuating a misquoting. Recall that "other drinks" here means other categories of alcohol, not fruit juice. Keeping it in only clarifies things for those readers who knew that Auld et al meant "other alcoholic drinks" but sure doesn't help things for those who didn't know it.

Further, it's Chris Auld that said "very misleading". I'd said, and continue to say, "screamingly wrong". I was just space-constrained in the letters section.

If I had to guess what happened in the Sellman and Connor press release, I'd guess something like the following - I could pretty easily be wrong though and would happily take correction. Sellman and Connor both got mad that John Key said minimum pricing wouldn't do much to curb heavy drinkers' consumption, they ran a Google Scholar search to find some estimate they could use to beat him up with, gave the paper the most cursory skim to find a line they could use, and then ignored the rest of it. They might not have even noticed the 3.4% estimate further down the paper.

But even on this fairly benign story, there's just a shocking underling failure to put the number in context. Again, if you look at Wagenaar's meta-study, you just can't find a single estimate from any of the 100+ papers surveyed that puts alcohol demand as being relatively price elastic (ie absolute elasticity value  > 1.0); it's all degrees of inelasticity. And Sellman and Connor were happy to jump on a number saying alcohol's not just price elastic, it's really really price elastic. You simply cannot have any familiarity with this literature and expect that a price elasticity of -1.6 could possibly be right. It would be like claiming that acceleration due to Earth's gravity is fifty meters per second squared. You can't know anything about physics and think it plausible that acceleration due to gravity on Earth is fifty meters per second squared; you can't know anything about alcohol economics and think it plausible that the price elasticity of demand is -1.6. It's about that level of magnitude of wrong. And it's hardly "dismissing" the effects of gravity to point out that it's only really 9.8 meters per second squared either.

And this pair are the country's go-to experts on the evils of the booze.

Check your sources

Doug Sellman in the opinion section of today's Christchurch Press claims to have had his numbers right [not yet online]. Let's check the history here.

Here's Sellman and Connor's original press release:

Who is advising the Prime Minister on alcohol reform?

Mr Key announced today that he doesn’t believe that minimum pricing for alcohol will change the amount people drink.

“This is contrary to the scientific evidence base about alcohol pricing in general and minimum pricing in particular” said Prof Jennie Connor, medical spokeperson for Alcohol Action NZ.

“Mr Key states that what typically happens is people move down ‘the quality curve’ and still get access to alcohol. Where does this information come from? On the contrary, minimum pricing specifically targets the very cheapest alcohol options and is predicted to reduce average consumption by removing high-alcohol low-cost products from the market.”

“A recent Canadian study has shown that a 10% increase in the minimum price of alcohol reduces its consumption by 16% relative to other drinks”. [emphasis added]

“And these latest data are consistent with the scientific literature which indicates that increasing the price of alcohol has a positive impact on reducing heavy drinking”.

This is very clearly saying that there are very large price effects of increasing the cost of the lowest-priced alcohol. I had initially found the Newstalk ZB report and wondered whether she'd been misquoted, before finding the press release.

I wrote:

Connor has to have been misquoted here or the journalists left out a couple of subsequent clarifying sentences. The error is in the press release. Oh dear.

The link there is now deprecated, but the Scoop link still works.

In today's press, Sellman says that they had it right all along:

On July 3, 2012 we issued a press release recommending the government enacts a minimum price per standard drink of alcohol – to eliminate ultra-cheap drinks favoured by binge drinkers, young drinkers and heavy drinkers – and pointed to a Canadian study that showed ‘‘a 10 per cent increase in the minimum price of alcohol reduces its consumption by 16 per cent relative to other drinks’’. Our wording was based closely on the paper’s wording: “Longitudinal estimates suggest that a 10 per cent increase in the minimum price of an alcoholic beverage reduced its consumption relative to other beverages by 16.1 per cent (p0.001).”

Two days later Crampton wrote a damning critique of the press release on his personal blog, using the same arguments he later used in this Press article. However, it appears Crampton based his critique on a short Newstalk ZB news report of the press release, which quoted Jennie Connor saying, ‘‘studies show a 10 per cent increase in the minimum price of alcohol reduces consumption 16 per cent’’. Note: the reporter had cut off the words ‘‘relative to other drinks’’, which would indeed be wrong if she had said it.

Crampton’s blog piece, and his later Perspectives article, ridiculed the presumed mistake: ‘‘Can a 10 per cent increase in the minimum price of alcohol really reduce total alcohol consumption by 16 per cent?’’ he wrote. ‘‘No’’. But if he had taken the basic precaution of checking the primary source, our press release, he would have seen the words ‘‘relative to other drinks’’ and realised that we had not misquoted the Canadian study at all.

Thus Crampton’s main argument in the Press article was based on his own simple and avoidable mistake, which seems careless for a senior lecturer.

The problem isn't that the Newstalk piece left off the words "relative to other drinks" but that Sellman and Connor used that estimate as though it were relevant to average consumption and where "other drinks" would be interpreted as something other than other categories of alcoholic beverages.

Further, they might have noted that my post of 10 July quoted the press release accurately; my post of 5 July had cited the NewsTalk reporting.

If we look a bit further down the Auld paper, we see pretty clearly what Sellman and Connor had missed:

"The estimates indicate that a 10% increase in the minimum price of a given type of beverage reduced consumption of that type by about 16.1% relative to all other beverages, and a simultaneous 10% increase in the minimum prices of all types reduced total consumption by 3.4% (p<0.01 in both cases)."

Sellman and Connor were building a case in their press release that the Prime Minister was way off base in claiming that raising the minimum price would not have large effects on drinking. Whether "relative to other drinks" is included or not is irrelevant where the context suggests that "other drinks" means drinks other than alcohol.

And so I sent the letter below to the Press this morning:

Doug Sellman in Monday's Press claims to have had his numbers right all along. In his press release of 3 July, he and Jennie Connor wrote:

“Mr Key states that what typically happens is people move down ‘the quality curve’ and still get access to alcohol. Where does this information come from? On the contrary, minimum pricing specifically targets the very cheapest alcohol options and is predicted to reduce average consumption by removing high-alcohol low-cost products from the market.”

“A recent Canadian study has shown that a 10% increase in the minimum price of alcohol reduces its consumption by 16% relative to other drinks”.

The rather obvious interpretation of their release, which was highly critical of the Prime Minister's claim that minimum prices would not greatly affect consumption, was that we should expect a sixteen percent reduction in consumption of alcohol relative to other drinks were the minimum price of alcohol to rise by ten percent.

The paper on which their analysis was based does indeed have a quote that reads a lot like Sellman and Connor's. But, it refers to the effects you get if the price of one category of alcohol - like beer, wine, or spirits - rises relative to other categories of alcoholic drinks. It isn't talking about the consumption of alcohol as compared to fruit juice. This is obvious if we read the second clause of the sentence, where Auld and his coauthors write:

"The estimates indicate that a 10% increase in the minimum price of a given type of beverage reduced consumption of that type by about 16.1% relative to all other beverages, and a simultaneous 10% increase in the minimum prices of all types reduced total consumption by 3.4% (p<0.01 in both cases)."

In Monday's Press, Sellman claims not to have misquoted the Canadian study and that they had, all along, meant "relative to other drinks" to refer to other categories of alcohol. If so, it seems odd to have chosen that figure as being relevant to the argument they were building. It could be relevant if we were estimating the likely reduction in consumption of premixed "alco-pops" relative to other alcoholic beverages, but surely the total amount of alcohol consumed matters more than whether it is consumed in one type of alcoholic beverage rather than another. And, for total consumption, the 3.4% figure is the rather more relevant one.

I strongly encourage readers to read the paper on which Sellman's claims are based and to judge for themselves, rather than trusting either of us. An ungated version of it is available here: http://www.vsnews.fr/etudes/Does-Minimum-Pricing-Reduce-Alcohol-Consumption.pdf . Or, go to scholar.google.com and type "Does minimum pricing reduce alcohol consumption?" You will find that the authors there, like Sellman, favour minimum prices. I worry more about harms imposed on lower income moderate consumers of lower cost alcohol. How we weigh the tradeoff between reducing harms from heavy drinkers and reducing consumption benefits from poorer moderate drinkers is a fairly important discussion. But the case for a minimum price for alcohol ought not be based on an estimate of its effects that is roughly five times larger than that which can be supported by the evidence.

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.

Evidence and minimum alcohol pricing

Otago's Jennie Connor and Alcohol Action NZ's Doug Sellman are angry again. This time, because Justice Minister Judith Collins cited some Masters' research done at Massey AUT showing that students surveyed said they'd not change their binge drinking habits if prices increased; they instead want the government to rely on international peer-reviewed evidence based on actual consumption patterns rather than on surveys.

And fair enough.

Fortunately, we have some evidence ready at hand. Byrnes et al, 2012, Drug and Alcohol Review. They use Australian household surveys from 2001, 2004 and 2007 to see how changes in alcohol prices affect the number of reported days of no, low, moderate, and high alcohol consumption; they find that while price increases do reduce consumption, they tend to reduce the number of days of low consumption while not changing the number of days of moderate and high alcohol consumption. This would be consistent with binge drinkers dropping the occasional beer or wine with dinner to save up for the big nights out. If policy is more worried about binge drinking than about light drinking, this might matter.

It's also mildly amusing that an Otago healthists complains about policy being based on surveys. I wonder what Connor would make of her Otago colleagues' call for banning smoking outside of bars on the basis of a survey of thirteen youths recruited in part via Facebook; the youths reported in focus groups that they'd be less likely to smoke if they couldn't smoke outside of bars. Maybe that one's ok because it's published in a journal rather than being a Masters Thesis.

Connor also notes that heavy drinkers tend to purchase cheaper alcohol relative to moderate drinkers.

“It has been established that hazardous drinkers spend less per unit of alcohol than others, and drinkers compensate for price increases by shifting to cheaper drinks. In the United States, the heaviest 10% of drinkers spend approximately $0.78 per drink compared with $4.75 per drink for the lightest 50% of drinkers.”

This only is a relevant comparison if the heaviest drinkers and lightest drinkers are drawn from the same parts of the income distribution. Suppose for sake of argument that heavier drinkers are more likely to be drawn from poorer parts of the income distribution and lighter drinkers from higher income parts of the distribution. If that's the case, we would want to compare the price paid by heavy and light drinkers correcting for any differences in income. If people with demographic characteristics similar to the heaviest 10% of drinkers but who are light drinkers spend $1 per drink (just a guess here), then minimum prices pushing above that hit both heavy drinkers and light drinkers of modest income. I know that consumption benefits from alcohol count for zero in the healthist world, but they ought to matter for policy.

At least they're not today claiming that a 10% increase in minimum prices reduce consumption by 16%...

If this isn't a wowser, I don't know what is

The Press has a puff piece letting Doug Sellman explain how he's not a wowser.

In short, 'wowser' suggested Christian women and other busybodies who wanted to get between a man and his drink. And not just drinking but many forms of pleasure. When Australian artist Norman Lindsay was attacked over his nude paintings in the 1930s, he said, "I am sick and tired of this wowseristic country". To this day, Lindsay's authorised online biography has "irate wowsers" in North America burning his paintings.

Closer to home and in our time, Doug Sellman has had "wowser" thrown at him a few times over the years. Along with other, less polite words. All because he has talked back to the alcohol industry.

Ok. This from the guy who got mad about the Woodstock mixed bourbon and cola drinks not just because of the booze, but also because they encouraged teenagers to have sex with their friends' mothers. Here's Sellman in an oped from the Herald not too long ago:

Mr Kerr is saying these young people and women need to be more responsible in the face of aggressive targeted marketing. But the industry he is defending is cynically trying to convert these people into heavy drinkers. Is that socially responsible?

Alcohol advertising on TV has recently reached a point that one wonders whether it can sink any lower. The latest Woodstock advert[*] aiming to get boys to drink bourbon sweetened by Coca-Cola in a product called Woodstock, associates a can of Woodstock, a "woody", with a penile erection and not unsubtly is encouraging them to have sex with their best mates' mothers.

The ad also seems to be encouraging middle-aged women to get their teenage clothes back on and flirt with their son's best mates. I presume some would defend these adverts as responsible business practice and contributing to a healthy society.

So Sellman isn't leading an old time Christian Temperance Union crusade against fun.  As the billboard says, Yeah Right.

Here's Sellman warning that alcohol is a Group 1 carcinogen, comparing it to plutonium, and ignoring that birth control pills are in the same darned category.

Here's Sellman pushing for taxes on soda.

Here's Sellman saying that muesli is addictive.

Further in the Press article, Sellman says it's all about the science:

As wowser and related insults show, alcohol reform is an emotive field where much is at stake - revenue streams included. Sellman wants to emphasise the science.

"It perhaps needs to be stated my colleagues and I are not basing our suggestions for alcohol law reform on our own opinions or life experience," he concludes. "They are based on the best international scientific evidence available at the current time."

The Press piece had earlier quoted the press release from Doug Sellman and Alcohol Action NZ colleague and U Otago Prof Jennie Connor that grievously exaggerated the findings from Chris Auld's paper on the effects of minimum pricing in Canada. Maybe that press release was "based" on the best international scientific evidence in the same way that a lot of stuff on TV is "based on a true story". Because it sure misrepresents what Auld actually found. Why should we trust anything he or Connor say about alcohol?

* I'd posted the ad here when Sellman first posted this op-ed about the moral decay of today's youths and their mothers.

About that Canadian study...

Last week, anti-alcohol advocacy group Alcohol Action NZ put out a press release where the University of Otago's Jennie Connor was quoted:

"A recent Canadian study has shown that a 10% increase in the minimum price of alcohol reduces its consumption by 16% relative to other drinks".

I got in touch with one of the authors of what has to be the study to which she's referring.

Chris Auld reported that the -1.6 price elasticity figure indeed only refers to a measure of own-price elasticity. Except it isn't quite own-price elasticity. Because the estimation technique doesn't correct for substitution effects, it combines the own-price elasticity with cross-price elasticity from other products. Quoting from Chris, with his permission:

Suppose we have two types, 1 and 2. Demand for type 1 is x_1( m_1, m_2 ), presumably decreasing in own min price m_1 and increasing in the min price, m_2, of the other type. The panel models recover d(x1 - x2)/d(m_1), so they are not estimates of own-demand slopes. For example, we might estimate -1.6 if the own-elasticity is -0.9 and the cross-elasticity is +0.7. Since we are not controlling for the cross-price, nothing can be said from these models about the effect of increasing both minimum prices---it could be that total consumption is almost invariant to min prices, but we could still generate big estimates from these models if various types of alcohol are strong substitutes. Test statistics against the null that the total effect is zero are still valid, but it's easy to misinterpret what the estimates mean

Chris also confirms that the -0.34 estimate is the one that best reflects the expected effects of an across-the-board price increase like minimum pricing, but notes that the standard kinds of time series problems makes that estimate rather less robust than he'd like.

I think it's [the estimate] probably too high, although it may be in the ballpark - a variety of evidence does suggest that min price changes are quite effective in targetting heavy drinkers.

Wagneaar found -0.28 among heavy drinkers, so I'm less worried about potential lack of robustness around Chris's estimate; if every estimate of this sort has similar robustness issues, then we might worry about systematic overestimation of demand elasticity with publication bias.

Heavy drinkers who consume cheap alcohol will be targeted with minimum prices, but so too will moderate poor drinkers who choose cheap alcohol.

Chris says he's doing some theory work showing that:

the central planner would always like to impose minimum pricing but reduce conventional taxes when confronted by consumers who are heterogeneous in an underlying demand parameter and when externalities are nonlinear in consumption---because there is an externality on the quantity but quality choice, the planner would like people to drink less alcohol, but drink higher quality alcohol.

I agree with Chris on this one - I'd posted a pretty similar point last week. The New Zealand Drug Foundation should perhaps pay attention to this one: having a minimum price should be coupled with excise reductions, not increases; NZDF has been pushing for both a minimum price and an increase in excise. If the ex ante excise were seriously below the optimum, then I'd expect a model like the one Chris is likely working up to say instead that minimum pricing lets us increase excise less than we otherwise would. But aggregate excise here isn't far out from actual external harms from alcohol. And I still worry about effects on moderate drinkers of lower income. The policy seems likely to be severely regressive.

Jennie Connor really should retract her press release or issue a correction. It leads people to believe that a minimum price will have far more effect on harmful drinkers' consumption than can be supported by the evidence. Otherwise, how much weight should anybody place on any "fact" claimed by Jennie Connor in her press releases?

In other scorekeeping, Ross Bell is right and John Key is wrong: a minimum price will increase the average quality of drink consumed, not reduce it. Here's Key:

"Instead of buying a $10 bottle of wine that might go to $15, they'll buy a $5 bottle of wine that'll cost $10. Their outlay is the same, the quality of what they're buying is worse," John Key said.

Competition among retailers, distributors, and producers ensures that drinkers get at least the minimum price's worth of value for the drink they're consuming except where there are other restrictions in the system that allows agents to accumulate rents.


But in that same article, Bell underestimates the number of standard drinks in a bottle of wine; this has the effect of reducing the perceived effect of a minimum price. Bell writes:

If the Government were to set the minimum price for alcohol at $1.50 - a reasonable and workable price - it would mean a seven-standard-drink bottle of wine could not be sold for less than $10.50.

Most bottles of wine are closer to 8 standard drinks than to 7. I had a quick flip through our wine rack. A Pegasus Bay riesling came in at 6.6 standard drinks. Nothing else in the rack rounded to 7 - everything else rounded to 8, except a few Aussie reds that rounded to 9. 8 standard drinks at a $1.50 minimum price is $12, not $10.50. And, though I'm a moderate high-income drinker, I do often buy bottles of wine in the $10-$12 range. The Montana Classics range on special for $9 is typically great value; I never feel bad about using third of a bottle in cooking at the price, and a glass while cooking is generally decent too.

Bell cites a Scottish government study suggesting that moderate drinkers won't reduce their consumption by much in absolute terms while heavy drinkers will have massive reductions in absolute consumption. If that one's based on Sheffield, and if Sheffield there is assuming constant elasticity across moderate and heavy drinkers, I wouldn't put much weight on it. Sometimes Sheffield estimates differential elasticities, sometimes they just assume constant elasticities. I'm not sure what they're doing in this particular one. And I also worry too about differential patterns in how people reduce their consumption. The Australian study I'd cited last week showed that most of the action in price increases is in reducing the number of days of light drinking rather than reducing the amount of heavy drinking, though there are other studies suggesting reasonable price elasticity of binge drinking. 

Finally, Bell cites BERL's (adjusted) figure on alcohol-related harm: $4.4 billion. That's disappointing. Ross, please remember that that study is just terrible. Again,

• They count the VSL from lives lost while simultaneously counting the total value of forgone production from premature mortality. The Ministry of Transport, who puts out the VSL measure, never does this when they tabulate the social costs of car crashes. They count the value of lives lost in accidents, the cost of injuries, and the value of production forgone due to injuries, but they don't count forgone production from those who die. The measure of the value of a statistical life is inclusive of the measure of forgone production. BERL says that VSL costs are $1.52 billion and that labour costs, mostly from deaths, is $1.48 billion. 


• Where their model study, Collins and Lapsley, counted both the health benefits and the health costs of drinking and took a net measure of costs to the health care system, BERL took a one-line assumption that harmful drinking can never have any health benefits as justifying a move zeroing out any of the aetiological fractions where alcohol reduced costs. This was absurd and points strongly to that they just wanted to give the Ministry of Health the very very large number that the Ministry of Health wanted. Even drinking that is on net harmful can have a mix of underlying positives and negatives. 


• They everywhere conflate private and social costs. Ross, you probably want to include all the costs that drinkers impose on themselves. And that's fair enough where you accurately characterise those total costs as mostly consisting of costs drinkers impose on themselves. But neither of the points above have anything to do with that. It's just poor method designed to inflate reported costs. And repeating the "costs New Zealand" line without the qualification makes people think that you're referring to a cost to the taxpayer through the health system rather than a cost drinkers impose on themselves - it's misleading; I hope not purposefully so.

Peter Dunne seems pretty sensible on this one, even if I do curse his name each and every time I want to get cold medicine that works.

"To say that we'll have a minimum price of $12 for a bottle of wine because people who can't afford to pay $12 shouldn't pay a lesser price, but Chardonnay socialists who can pay $25, $30 for a bottle of wine will still be able to get their wine. I think that's a really elitist and ridiculous argument."

The policy would reduce some harmful consumption, but it would also reduce some reasonable consumption from lower income drinkers - and from a few higher income cheapskates like me. We either need more serious work showing that the harms prevented outweighs the harm imposed by the policy, or at least coupling the policy with transfers to those negatively affected.

Odoriferous statements

Prime Minister John Key said he didn't think minimum pricing would do much to curb heavy harmful drinking. Jennie Connor is quoted in a press release excoriating Key:

Mr Key announced today that he doesn't believe that minimum pricing for alcohol will change the amount people drink.

"This is contrary to the scientific evidence base about alcohol pricing in general and minimum pricing in particular" said Prof Jennie Connor, medical spokeperson for Alcohol Action NZ.

"Mr Key states that what typically happens is people move down 'the quality curve' and still get access to alcohol. Where does this information come from? On the contrary, minimum pricing specifically targets the very cheapest alcohol options and is predicted to reduce average consumption by removing high-alcohol low-cost products from the market."

"A recent Canadian study has shown that a 10% increase in the minimum price of alcohol reduces its consumption by 16% relative to other drinks".

"And these latest data are consistent with the scientific literature which indicates that increasing the price of alcohol has a positive impact on reducing heavy drinking". [emphasis added]

When I saw the release [HT: ed.co.nz], something seemed awfully odd about the bolded quote. What's the reference category, fruit juice? What's meant by "relative to other drinks"? So I dug around a bit for the work she's citing.

Connor is almost certainly referring to this Canadian study, which does argue in favour of minimum pricing. But compare their numbers with the bolded quote above.

The estimates indicate that a 10% increase in the minimum price of a given type of [alcoholic] beverage reduced consumption of that type by about 16.1% relative to all other  [alcoholic] beverages, and a simultaneous 10% increase in the minimum prices of all types reduced total consumption by 3.4% (p<0.01 in both cases). The first estimate may overestimate minimum price effects because it incorporates compensatory increases in consumption of all other beverages. The estimate of the effect of across-the-board changes in minimum prices on total consumption will be biased to the extent that the extra structure we imposed on the model is unrealistic.

Connor is citing the results from the own-price study as being the estimate of the effect of the across the board increase.

Doug Sellman, in the same press release, says

"The PM's statements reek of alcohol industry influence."

As for the bouquet emanating from the Connor/Sellman press release...

Price elasticity of alcohol demand [Updated]

Otago's Jennie Connor cites some numbers on the elasticity of alcohol demand with respect to price that just seem off [HT: ed.co.nz].

But Professor of Preventive and Social Medicine at Otago University, Jennie Connor, says price does influence alcohol consumption.
She says studies show a 10 percent increase in the minimum price of alcohol reduces consumption 16 percent.
Professor Connor says it's a very efficient and effective way of reducing problems from alcohol, because it targets heavy drinkers the most.

I've been citing the Wagenaar meta-study results showing an aggregate alcohol demand elasticity of -0.44; she's saying it's -1.16 -1.6. There's a bit of a gap there.

When I look at Table 1 of Wagenaar's metastudy of 112 different studies of the price elasticity of demand, I can't find a single one that has an aggregate elasticity lower than -0.92 at the lower end of the confidence interval; the lowest point estimate is -0.84. Recall that you need to hit -1 to have a product that's price elastic. But those are aggregate estimates; maybe there's just something different about elasticity at the bottom end of the price distribution.

So let's have a look at a very recent Australian issues paper examining the case for minimum pricing. This one comes from the Australian National Preventative Health Agency. What do they say about demand elasticity at that end of the distribution?

First, we have to be awfully careful in distinguishing between own-price and aggregate category effects. If you look at the effects of a price increase in one category of product, you'll likely overestimate aggregate price responsiveness because price-sensitive shoppers will flip to another alcohol product category if one category's prices change.

Who does the Australian National Preventative Health Agency cite? Wagenaar, like I do: Wagenaar reports aggregate elasticity across all alcohol categories. They cite two other meta-studies, one of which, Gallet, also reports an aggregate category elasticity that's pretty much identical to Wagenaar's. Where Wagenaar gets -0.51, Gallet gets -0.52.* The last one only reports elasticity by category, which is next to useless for reckoning changes in response to minimum prices or cross-category excise increases, but within-category findings are about the same as Wagenaar and Gallet were getting in those kinds of estimates - more elastic than aggregate elasticity, but still nowhere near -1. Wagenaar gets -0.8 for spirits; people shift from spirits to other products more quickly when the price of spirits jumps.

Next, ANPHA cites some Sheffield figures on aggregate price elasticities for overall alcohol consumption: -0.47 for moderate drinkers and -0.21 for hazardous and harmful drinkers. They note too that, when we look at own-price elasticity within product categories, hazardous and harmful drinkers are more price elastic than moderate drinkers: they're more likely to shift product categories. But that tells us zilch about what harmful drinkers do in response to a price increase for the entire product category; it would be misleading to use this kind of data to claim that harmful drinkers are the most price responsive. They're most price responsive when their preferred brand or product changes in price but they're also least responsive to aggregate changes in alcohol prices.

Finally, ANPHA look at some evidence from Canadian experiments with social reference pricing. At page 16, they cite evidence from British Columbia where a 10% increase in alcohol's minimum price resulted in 3.4% reduction in aggregate consumption: again, a finding consistent with the numbers I'm citing, and not consistent with Connor's.

ANPHA cite a bunch of other Sheffield simulation results showing relative price inelasticity but greater simulated total consumption changes among harmful drinkers than among moderate drinkers. Simulation results here are going to be pretty sensitive to parameter estimates, but it's also the case that a smaller percentage consumption reduction among heavy drinkers than among moderate drinkers can easily generate larger total consumption decreases among heavy drinkers.

The ANPHA issues paper doesn't make policy recommendations; it just looks at issues around minimum pricing. But they do include in their appendix a paragraph noting their prior recommendation: that alcohol move to a tiered volumetric tax that looks an awful lot like New Zealand's current system where spirits are more heavily taxed per unit alcohol than beer and wine, which are more heavily taxed per unit alcohol than low-alcohol products. I'm not endorsing the ANPHA paper or its recommendations,** but its survey around the price elasticity of demand is pretty much what I've been finding in my own searches through the literature. And I can't find anything in it that would support suggestions that alcohol consumption is relatively price elastic to regulated minimum prices.

I'd love to know where Connor's getting her elasticity estimates. They are completely outside of any plausible range. Again there is not a single paper among the 112 papers cited by Wagenaar that comes within cooie of the numbers she's suggesting would here apply; not a single one finds that aggregate alcohol demand is relatively elastic. O'Connor's suggesting an absolute price elasticity of demand of 1.16 1.6. Zero of the 112 cited by Wagenaar finds an absolute elasticity greater than 1. ANPHA does not cite a single finding suggesting an absolute elasticity greater than 1. Maybe there's a study out there somewhere that supports it, but I'd be awfully uncomfortable being cited in the press using number that are that far out of whack from the rest of the literature.

Finally, Connor says that minimum pricing targets heavy drinkers the most. It's true that they'll take the biggest dollar hit from an increase in minimum prices. But they are still less responsive relative to their consumption than are moderate drinkers. Imagine, for instance, claiming that rich fat people are most affected by a 100% tax on food because they wind up having the biggest increase in what they spend on food. Yeah, it's true. But the smaller absolute reduction in the quantity consumed by poor thin people matters too, especially if they cut their consumption by a much larger proportion than do the rich folks.

UPDATE: I've found the study Connor is citing, or at least I think I have. And, I think it's the same one that ANPHA is citing. Remember how I noted at the start that you have to be careful to look at aggregate changes rather than just own-price? Well, ANPHA was careful about that. Connor is citing the figure from the same study that looks only at what happens to, say, beer consumption if you hike the price of beer while leaving the price of wine constant. Suppose Honda increased the price of its cars 10% and we saw a 16% drop in Honda sales as consumers shifted to Toyotas; it would be a bit nuts to sell that as saying that a 10% tax on all cars would reduce aggregate car purchases by 16%. Here's the original paper:

The estimates indicate that a 10% increase in the minimum price of a given type of beverage [EC: eg, spirits, beer, wine] reduced consumption of that type by about 16.1% relative to all other beverages, and a simultaneous 10% increase in the minimum prices of all types reduced total consumption by 3.4% (p<0.01 in both cases). The first estimate may overestimate minimum price effects because  it incorporates compensatory increases in consumption of all other beverages. The estimate of the effect of across-the-board changes in minimum prices on total consumption will be biased to the extent that the extra structure we imposed on the model is unrealistic. 

Connor has to have been misquoted here or the journalists left out a couple of subsequent clarifying sentences. The error is in the press release. Oh dear.

Previously:

• Minimum Pricing
• Correlation, causation and alcohol
• Drinkers' utility
• Alco-pops and minimum pricing
• The whole darned alcohol tag
• Moderate drinking and health

*Note that I've been citing -0.44: mean elasticity across all the estimates is -0.51, but Wagenaar gives -0.44 for total alcohol after adjustment for study characteristics.

** In particular, arguments around increasing the price of the lowest-cost products in Australia, where the WET means that cask wine can be very cheap, just don't translate to the New Zealand environment where we already have a tiered volumetric excise regime. I also am far more sceptical of results coming from Sheffield's simulation work than they seem to be.