Skip to main content

Food, obesity and naughty statistics

We've just had the latest report for the government to ignore on the National Food Strategy. You can see the BBC coverage of it here

I absolutely agree with finding ways to encourage people to eat healthier food, and I have no particular aversion to taxing sugar and salt in manufactured food. Don't get me wrong. I love the occasional burger and chocolate biscuit and suchlike. But I'm all in favour of keeping the junk in moderation, and clearly a lot of people need help with that.

So it's not a case of disagreeing with the report or its findings. But I do think they have been guilty of misuse of statistics in presenting their results.

I had a look at the review's report (176 pages in the 'evidence' part alone, though it's not quite as scary as it sounds as each page is essentially a slide, often with graphics). The evidence is divided into two main sections: nature and climate, and health. My issue is with something in the health section, though I do note in passing that the nature section isn't always clear about what it's saying - so, for example, page 15 tells us that 'the amount of land under organic production is declining' - my immediate reaction is that this is a good thing, as it means the land is being used more efficiently, but I'm not sure if that's what the report's writers had in mind.

But the naughty bit I'm particularly interested in is page 100, a version of which provides the only data on the BBC News story and which was brought up as a major item in discussion with the report's lead author Henry Dimbleby on the radio this morning. Here's the original from the report:

Relative price per calorie of different foods (National Food Strategy Independent Review)

There's a lot of detail here, but the main takeaway is that healthy veg like broccoli cost around 3 times as much per calorie than junk food. That's fine, apart from their being other healthy veg like lentils which are cheap per calorie and no one mentioned that, but it's the way this statistic was used that's dubious. We were told that this means that eating healthy food cost more than eating junk. But a major point of eating healthily is to eat fewer calories - so it's senseless to make a comparison on cost per calorie. What's important is cost per meal - and a plate of homemade vegetable curry, say, costs a lot less than a plate of junk food. 

This is a worthy cause. But using misleading statistics is not the way to support it. In fact, it gives entirely the wrong message, because it suggests to someone on limited income that it's cheaper to live on junk food, which just isn't true - because eating junk food results in eating far more calories.


Popular posts from this blog

Is 5x3 the same as 3x5?

The Internet has gone mildly bonkers over a child in America who was marked down in a test because when asked to work out 5x3 by repeated addition he/she used 5+5+5 instead of 3+3+3+3+3. Those who support the teacher say that 5x3 means 'five lots of 3' where the complainants say that 'times' is commutative (reversible) so the distinction is meaningless as 5x3 and 3x5 are indistinguishable. It's certainly true that not all mathematical operations are commutative. I think we are all comfortable that 5-3 is not the same as 3-5.  However. This not true of multiplication (of numbers). And so if there is to be any distinction, it has to be in the use of English to interpret the 'x' sign. Unfortunately, even here there is no logical way of coming up with a definitive answer. I suspect most primary school teachers would expands 'times' as 'lots of' as mentioned above. So we get 5 x 3 as '5 lots of 3'. Unfortunately that only wor

Why I hate opera

If I'm honest, the title of this post is an exaggeration to make a point. I don't really hate opera. There are a couple of operas - notably Monteverdi's Incoranazione di Poppea and Purcell's Dido & Aeneas - that I quite like. But what I do find truly sickening is the reverence with which opera is treated, as if it were some particularly great art form. Nowhere was this more obvious than in ITV's recent gut-wrenchingly awful series Pop Star to Opera Star , where the likes of Alan Tichmarsh treated the real opera singers as if they were fragile pieces on Antiques Roadshow, and the music as if it were a gift of the gods. In my opinion - and I know not everyone agrees - opera is: Mediocre music Melodramatic plots Amateurishly hammy acting A forced and unpleasant singing style Ridiculously over-supported by public funds I won't even bother to go into any detail on the plots and the acting - this is just self-evident. But the other aspects need some ex

Which idiot came up with percentage-based gradient signs

Rant warning: the contents of this post could sound like something produced by UKIP. I wish to make it clear that I do not in any way support or endorse that political party. In fact it gives me the creeps. Once upon a time, the signs for a steep hill on British roads displayed the gradient in a simple, easy-to-understand form. If the hill went up, say, one yard for every three yards forward it said '1 in 3'. Then some bureaucrat came along and decided that it would be a good idea to state the slope as a percentage. So now the sign for (say) a 1 in 10 slope says 10% (I think). That 'I think' is because the percentage-based slope is so unnatural. There are two ways we conventionally measure slopes. Either on X/Y coordiates (as in 1 in 4) or using degrees - say at a 15° angle. We don't measure them in percentages. It's easy to visualize a 1 in 3 slope, or a 30 degree angle. Much less obvious what a 33.333 recurring percent slope is. And what's a 100% slope