Thursday, 5 July 2018

Chile's soda tax "success"

The sugar tax junk science just keeps coming. It's amazing how hard it is to find evidence that taxes on sugary drinks has any effect on consumption, let alone calorie intake or obesity.

First we had the Mexico study which claimed to have found a 6 per cent drop in sales. This was plausible enough for a 10 per cent tax, but it turned out to be false. Per capita consumption was almost exactly the same after the tax was introduced as it had been before.

Then we had the study of Berkeley, California where sales fell in the town of Berkeley but rose in the surrounding area where the tax was not in force. Thanks to out-of-town shopping and increased consumption of substitute beverages, the tax led to more calories being consumed in soft drinks than before.

Daily usual taxed beverage intake was 121 g/d pre-tax and 97 g/d post-tax (−13.3%, p = 0.49), while mean caloric intake of taxed beverages went from 45 kcal/d to 39 kcal/d (−19.8%, p = 0.56) (Table 1); neither difference is statistically significant. From the pre- to post-tax period, mean volume of untaxed beverage intake went from 1,839 g/d to 1,897 g/d (+3.2%, p = 0.21). Reported mean caloric intake of untaxed beverages rose from 116 kcal/d to 148 kcal/d (+27.6%, p = 0.02).

It's a pretty dismal record but the crusade for sugar taxes marches on regardless thanks to the dozy media and headlines like 'Sugar tax in Mexico cuts sales of sugary drinks by 12 per cent' and
'First US sugar tax sees soft drink sales fall by almost 10%, study shows'.

Yesterday saw the publication of a study of Chile's soda tax and it's a belter if you like quackery. Chile's tax change was so minor that no reasonable person would expect to see much effect. The tax on sugary drinks rose from 13 per cent to 18 per cent and the tax on diet drinks dropped from 13 per cent to 10 per cent. In practice that means...

... the tax change, if fully transmitted to the consumer, would increase the prices of a 500ml sugary beverage from 500 pesos (£0.60) to 525 pesos (£0.62), and it would drop the price of an equally priced non-sugary beverage to 485 pesos (£0.57).

A 2p increase on a 60p half-litre of Coke isn't much of a deterrent. At best, you might expect sales to fall by 4 per cent. In the event, it doesn't seem to have managed one per cent.

For some reason, the tax has been evaluated by some academics at York University and they have been helpful enough to show us the consumption figures:


If you can't see any difference in consumption after the tax (dotted red line), you are not alone. Neither could the researchers...

For all soft drinks and for the relevant soft drink subcategories (except the no-tax soft drinks, which show a trend increase), it is hard to detect a clear overall time trend based on pure visual inspection alone. While the peaks in the data certainly become less pronounced over time, so have some of the troughs. It is equally difficult to discern an obvious pre- versus post-tax pattern in any of the categories.

That should have been the end of it. Consumption was unchanged and so the tax can't possibly have had any obesity which, let's not forget, is supposed to be the primary outcome. But no one goes home empty hand in the 'public health' racket, so they did some modelling. What kind of modelling? They don't say, but it had one hell of an effect because...

Our main estimates suggest a significant, sizeable reduction in the volume of high-tax soft drinks purchased (21.7%)
 
What?! Consumption fell by 21.7 per cent as a result of a five per cent tax rise?! In what universe does that sit with basic economics and common sense, let alone tally with the graph that we can see with our own eyes?

It's as if 'public health' research is one big wind-up and they're seeing how much they can get away with before they get busted. But there's no sign of that happening if the Telegraph's coverage is any guide...

Major new study shows Chile's sugar tax has sharply reduced sales of sugary drinks

Chile’s sugar tax seems to be successfully chipping away at the nation’s preference for all things sweet, according to new research. The findings will likely encourage other countries battling their own obesity epidemics.

The study by an international team led by researchers at the University of York looked at sales of sugary drinks in Chile between 2011 and 2015.  It found purchases fell by 21.6 per cent following the introduction of the tax.

And, inevitably...

The researchers called for sugar taxes to be applied to food and well as drinks. "Policy to reduce sugar intake should not only target the sugar contained in soft drinks, but also in food," said Prof. Suhrcke.

Chile now joins the growing list of sugar tax success stories along with Mexico, where sugary drink consumption was unaffected, and Berkeley, where people drank more calories after the tax came into effect. In both cases, modelling by activist-academics conjured successful outcomes out of thin air.

Now we have the Chilean miracle in which a small tax rise had essentially no effect on anything but modelling turned this into a 22% decline in consumption. The phrase 'junk science' doesn't really do this justice. 'Junk science' implies some kind of methodological flaw or statistical trick. The Chile study is just a... lie. It's literally fake news.

Campaigners for sugar taxes are in a fantasy world of their own making. They model the effects of the tax when they are lobbying for it and then, once it has been introduced and achieved nothing, they model it again to prove that it worked. Perhaps they will one day model a decline in obesity and a decline in mortality. If we can have an imaginary decline in soda consumption, why not have some imaginary weight loss to go along with it?

No comments: