The paper and the rhetoric

From today's New Zealand Medical Journal:

The University of Otago's John Langley and and Pauline Gulliver find that alcohol was "involved" in 23.6% of non-fatal assaults by males; 13.1% of non-fatal assaults by females. Table 1 shows assaults to be relatively concentrated among Maori (31.7% of male assaults, 47.8% of female assaults; Maori represent about 15% of the population by the 2001 Census) and among the poorest cohorts - the authors note decile 9 males have assault rates 26 times the average in decile 1. There is no econometric analysis allowing for the disentanglement of ethnicity and income effects; Maori are more heavily represented among the poorest cohorts. Note further that "involvement" here also refers to the victim, not necessarily the perpetrator, unless the victim and the perpetrator co-identify (two people in a fight, for example).

We also have no clue about base rate alcohol consumption. If assault is concentrated among the poorest, and among Maori, if we were to take a random snapshot of that cohort during the day and ask "Have you had alcohol recently?", we don't know what the answer would be. What is the rate of alcohol involvement in other non-violent activities among the at-risk cohort: alcohol-involved rugby-watching, alcohol-involved friendly gatherings, and so on. I'd expect it would be higher than the population average, but that's just a hunch. If a high proportion of activities undertaken in this population group could have the "alcohol involvement" tag added, it's hard to draw causal inferences about the effects of alcohol on assaults from simply observing that between a fifth and a quarter of incidents involve alcohol.

In noting the study's limitations, the authors write:

We have no way of knowing whether alcohol involvement played a casual role in the assaultive injuries described in this paper. It could well be, for example, that many of the males just happened to be drinking at the time. On the other hand there is evidence from elsewhere that being intoxicated increases one’s risk of becoming a victim of assault.⁹ Alcohol misuse is also a distal risk factor for assault, where a pattern of heavy episodic drinking has been associated with a threefold increase in victimisation involving drinking.¹⁰

And today's headline: "Booze is fuelling rise in serious assaults" . From the newspaper:

A rise in serious assaults among young Maori and Pasifika males to ''disturbingly high levels'' has researchers calling for the Government to take action over alcohol.

Emeritus Professor John Langley, of the University of Otago's Injury Prevention Research Unit, says assaults are rising steadily and blames the Government for their failure to curb alcohol consumption.

A study published today in the New Zealand Medical Journal, co-authored by Langley and Dr Pauline Gulliver, examined the 8006 serious non-fatal assaults between 2000-2009 and is the first comprehensive statistical analysis of this category of violence in over two decades.

 ...

Excessive alcohol consumption was a common factor in the assault incidents, which frequently featured young to middle-age males beating up similarly aged males, Langley said.

''One of the key messages from the paper is 80 per cent of the problem is males. Most of those males are being assaulted by other males, and guess what the fuel is: it's alcohol.''

He said the Government needed to make alcohol harder to buy, and said their lack of action to date had been ''inexcusable''.

The article continues in that vein, quoting the study's authors drawing an awfully long policy bow from their paper's findings.

Things that definitely are NOT in the NZMJ paper:

• Any assertion of causality regarding alcohol in this data;
• Any discussion of time trends in alcohol's involvement in assaults. They give time trends on the rate of assaults, but nothing on time trends for alcohol's involvement;
• Any reason to believe that alcohol consumption has increased among the at-risk cohort over the period.

Here's the last data I'd seen on hazardous drinking prevalence sorted by ethnic group:

Table H6.2 Age-standardised potentially hazardous drinking prevalence rate (%), for adult drinkers, by ethnic group and sex, 1996/1997, 2002/2003, 2006/2007

	European/Other	Māori	Pacific peoples	Asian	Total 15+
1996/1997
Male	31.0	46.1	48.2	11.6	30.9
Female	12.0	30.6	20.8	5.1	13.3
Total	21.6	38.3	38.1	9.4	22.3
2002/2003
Male	29.9	42.4	44.1	11.5	30.6
Female	13.3	24.1	24.3	4.8	14.2
Total	21.7	32.9	36.1	8.6	22.5
2006/2007
Male	32.1	46.8	46.6	12.9	31.2
Female	14.5	28.5	25.8	3.8	14.7
Total	23.1	37.5	37.7	8.9	22.9

Source: Ministry of Health
Notes: (1) Rates are age-standardised using the WHO world population. (2) People who reported more than one ethnic group are counted once in each group reported.

The prevalence of potentially hazardous drinking dropped from 1996 to 2002 among Maori before rising again to roughly its 1996 level by 2006. The NZMJ paper has serious assaults by bodily force (ie a fight without weapons) sharply increasing from 2003 onwards, so that's at least not inconsistent with the alcohol hypothesis. But look at the rates: prevalence of hazardous drinking went from 32.9% to 37.5% among Maori over the period (with much much smaller increases for other groups). A fourteen percent increase. Serious assaults using bodily force more than doubled (other categories were flat).

Further, where the rate of potentially hazardous drinking is pretty high for some cohorts, it would be more surprising to find an absence of alcohol use. What's the rate of alcohol involvement in watching rugby within that cohort? How can we say anything about causality or draw strong policy conclusions?

I guess the NZMJ piece is a convenient hook, but it sure doesn't look like it provides much scientific basis for the policy conclusions they're hanging on it. And I fully expect it'll be cited often as evidence favouring cracking down on alcohol.

A symposium, of sorts

The latest issue of the New Zealand Medical Journal features three papers on alcohol policy, including one from Matt Burgess, Brad Taylor and me, along with a commissioned editorial piece on the set. I have not yet had a chance to read the other two papers in the series but the editor of the journal kindly forwarded along a copy of the editorial piece late Thursday night.

Doug Sellman, lead author on the editorial piece, says about what I expected he would say about our work on alcohol.

Our piece in the NZMJ contrasts the standard economic approach to costs and benefits with that employed by BERL in their work. We worked through the different cost categories in the BERL report to illustrate the differences between a standard economic approach and the cost of illness method they used before spending a bit of time on the importance of marginal analysis rather than measuring total benefits and total costs of anything.

Sellman's piece, or at least the part of it criticising us rather than lauding the other two papers, begins with* a critique of our focus on external costs rather than costs borne by drinkers themselves; he pitches this as being responsible for the $4 billion difference in measured cost. I would note here that about a billion and a half of that $4 billion difference comes from BERL having double-counted intangible costs of statistical lives lost with forgone earnings. Even if your focus were entirely on total costs, there's a big chunk of that total figure that's just wrong.

I'm also not sure if he's amplifying for rhetorical effect, didn't understand the point, or whether we didn't phrase it clearly enough. But he writes:

The narrowness of the Crampton group’s approach is exemplified in the statement that “the only policy-relevant costs [of a fatal drink driver accident] are those imposed on emergency services in responding to the accident”. Equally the lost productivity through mortality reveals the dismal view from the world of this particular economic approach: early death is not seen as a cost because the economic unit (the deceased person) can simply be replaced.

In the case of drink driving accidents, we were very clear that deaths to those outside of the drinker's vehicle impose very large costs that are definitely deemed external and policy relevant. But if you were considering a single vehicle accident with a solo driver where nobody else was hurt and only the driver's own car was wrecked, then we would only count the costs to emergency services. There costs of deaths associated with that kind of crash remain very real, but if you want to count them, you have to also count the benefits enjoyed by those who took similar risk and didn't have an accident.

Similarly, Doug doesn't quite get why we discounted costs of forgone output. BERL used a measure of GDP per capita as forgone output rather than using the deceased worker's prior wages; that addition requires very strong assumptions around worker irreplaceability and capital-labour complementarity. But the main reasons we discounted lost output were first that it's double-counted with the intangible costs of lives lost, so it should be reduced even if you want to count private costs, and second because it's largely a cost borne by the drinker himself.

But here's my very favourite paragraph in the whole thing.

From a non-economist standpoint Crampton et al would appear to be the fundamentalists in this debate and their conclusions need to also be considered in the context of their receiving funds from an alcohol industry, which benefits from their conclusions. Further, it is important to note that “standard (neoclassical) economic approaches” are coming under increasing scrutiny and criticism, particularly following the recent global financial crisis, which was not predicted by “standard” economic models. New economic models based on better science and more rigorous mathematics are now progressing.5 [cite to Keen!]

I'm pretty sure that these can't all be true at once:

1. I'm a fundamentalist
2. I'm bought out by industry, saying whatever they want
3. We should throw out neoclassical economics because it yields conclusions like mine and the financial crisis too.

I suppose 1 and 3 could go together if I'm a fundamentalist economist. But the thing is, you can't really buy out a fundamentalist. A true zealot can be encouraged to spend more time on one area of work rather than another [and a consultancy contract that needs to get finished, earthquakes or not, does sharpen incentives on that front], but you can't buy a fundamentalist's conclusions. It's perhaps worth noting, again, that the net effect of industry funding on conclusions, when it comes to my analysis of the BERL study, was to substantially increase the measured external costs of alcohol use: thoroughly understanding the model on which the BERL study was based led us to find an error in our prior unfunded work - one not noted either by BERL or by Marsden Jacob in its $60k hatchet job on that prior piece.

* Actually, it begins with Doug making a trivial but risky error: he says that BERL produced its report for the Law Commission's review of the alcohol literature. I understand that the Law Commission, back in 2009, sent out a couple of threatening letters when they were characterised as having commissioned the BERL report. I doubt it'll happen here, because LC isn't being criticized (incorrectly) for having commissioned a shonky report. They didn't commission a shonky report; the Ministry of Health and ACC did. The Law Commission relied on a shonky report. That's different.