Junk science and booze tax - a study in spin
Where's the beer?
With the evidence base in Part A looking so shaky, I'll forgo an analysis of Part B, the complex "predictive" model the Sheffield researchers derived from the evidence.
One snippet suggests that its headline accuracy may be optimistic. The Sheffield researchers' guesstimate of the affect of an advertising ban ranges from a 26.9 per cent fall to a five per cent increase in consumption, and of "financial value of harm avoided over ten years" from a -£44bn to +£9.5bn. In other words, the range is so huge, they can't predict whether a policy proposal will make things "better" or "worse". Some model.
From your correspondence, I know there are many experienced business and financial modellers amongst Reg readers, so if you're brave, you can download it here and let me know.
But let's look at how the wobbly evidence base coalesced into policy proposals, issued in a breezy 15-page summary document. Keep a look out for weasel words.
Evidence statement three is one to treasure:
"There is low quality but demonstrable specific evidence to suggest that minimum pricing might be effective as a targeted public health policy in reducing consumption of cheap drinks."
Or, translated into plain English: "Our low quality evidence can only produce a flimsy conjecture." That's followed up with an odd assertion that's so completely unrelated to any of the research, one can only presume it was designed for the benefit of Government spin doctors:
"There is also evidence to suggest that such a policy may be acceptable to many members of the community."
So a policy is "sellable"? This comes out of the blue. Nothing in the study supports this, and as we've seen, evidence in both parts A (the meta-meta-study) and B (the model) directly contradicts this.
Other statements offered are plain contradictions. Here's a good example:
"Evidence statement 13: There is consistent evidence to suggest that alcohol consumption is associated with substantially increased risks of all-cause mortality even in people drinking lower than recommended limits."
Let's hope nobody has read Part A, then. The only area the researchers felt they couldn't support is of crime. Here's "Evidence statement 22", in full:
No recent systematic reviews or meta-analyses were identified that examined the effects of alcohol on crime other than violence or on employment-related outcomes such as unemployment or absenteeism. There is sufficient non-review evidence to suggest that a significant proportion of criminal behaviour can be associated with alcohol misuse. However it is methodologically difficult to ascertain the alcohol attributable fraction for this association.
So here we have it: the government introduces a minimum price-per-unit for booze using as a justification research which doesn't support it. But it's not the last time we'll hear from the Sheffield School of Health, I suspect.
Having patted themselves on the back on creating a ground-breaking model (that's utterly useless) - "this is the first study to integrate modelling approaches intended to answer specific policy questions... this work has surmounted several of the important hurdles" - they go on to suggest "several areas for further research".
You can find it on Page 11 of Part B. It's not a modest list. The scope for policy-based evidence making is almost limitless. ®