The Economist can't think of any good arguments against trading organs

People have probably already seen the new posters for The Economist, frankly, I don't think any of the three issues they've picked are particularly interesting debates (should drugs be legalised, should prisoners be allowed to vote and should we allow trade in human organs). As far as I can see, all three are pretty much a slam dunk for the yes side. Anyway, it appears that, at least for the organ trading argument that the Economist agrees with me. Let's have a look at their 'against' arguments (you can see the poster here).

1. The British Medical Association says that allowing organs to be traded would put pressure on poorer people to sell.

Well.. yes, and allowing cars to be traded probably puts pressure on poorer people to sell. I have no idea why this is supposed to be a bad thing. Does the BMA have some reason to believe that poorer people would prefer having two functioning kidneys to money? That they should prefer this? Is there any particular reason we should believe the BMA is likely to have anything interesting to say about the question (they're medics, not economists or ethicists)

2. There are alternatives to a trade in organs. Countries in which people's consent to donating their organs is assumed unless they opt out have shorter waiting lists. 

Again, I have no idea why anyone would think this was an argument against allowing a trade in organs. Countries in which a trade in organs is allowed (ie, Iran) have even shorter waiting lists (ie, they don't have any).

There are alternatives to most things, the question is which alternative is best. (I would think presumed consent is even more of a slam-dunk than allowing trade in organs, except there's remarkably little evidence that it actually increases donations).

3. Legalising the trade in organs would turn the human body into a commodity. That is taking free markets too far.

To paraphrase "If we legalised trade in organs, then trade in organs would be legal. This is bad. Ner ner ner ner". This just doesn't even begin to be an argument against anything.

I'm not very surprised that the Economist agrees with me about legalising trade in organs, but surely they could have tried a bit harder to come up with some argument against? Or is it just that there aren't any?

Inadvertent Accuracy

Horrible article in the Telegraph, but with a great opening paragraph:

It is not necessary to be a conspiracy theorist to recognise that the General Medical Council's recent ruling to strike professors Andrew Wakefield and John Walker-Smith off the register had the fingerprints of the medical establishment all over it. 

Well... no, it's not. The medical establishment has struck off a doctor who performed unethical experiments on kids then misreported the results to make money out of them. That's pretty much what the medical establishment is for. Of course, I'm not entirely sure that's what Le Fanu means...

Correlations vs. Causation.

A while ago, I said I'd write a post with my favourite "things which are correlated". Well, now I've finally figured out how to do page-breaks, I guess it makes sense to write it now. Here are my favourites. Any suggestions as to why they might be correlated? (answers below the fold)

1. Countries which put Fluoride in the water have much higher cancer rates than countries which don't.
2. Schoolchildren's shoe size is very strongly correlated with their performance on spelling tests.
3. The number of shark attacks on a given day is strongly correlated with ice cream sales.
4. You are much more likely to wake up dehydrated if you sleep on a sofa than if you sleep on a bed.
5. The number of prostitutes working in a city is positively correlated with the number of policemen.

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Druids Demonstrate Regression to the Mean perfectly

I once heard of an experiment that a friend of mine (an anti-speed camera campaigner) used to do when he was giving a presentation. He would get everyone in the room to randomly generate a 2-digit number (not sure how, exactly, maybe he used to carry some sort of 10-sided dice with him). He would then give everyone who rolled more than 80 a big picture of a speed camera and got them to generate a second set of numbers. Lo and behold, only a small fraction (on average around 1/5) of those carrying speed camera signs had high levels of deaths. The speed cameras had worked!

This is the purest way I've ever seen to explain the phenomenon of 'regression to the mean'. It's a well-known phenomenon, and explains a lot of things, from why test scores at the worst schools tend to improve the next year, through why patients who visit a homeopath seem to feel better, to the Sports Illustrated Jinx.

However, the Austrian motorway authority seems never to have heard of it. They recently asked some druids to reduce the number of fatalities at a few accident blackspots by burying some magnetic slates. The results were a roaring success:

Austrian motorway authority ASFINAG said it was sceptical at first and kept the project a secret. But it went public after the druids’ efforts cut the number of deaths at the notorious crash site from six a year to zero in two years.

I don't think there's much more to say.

Why is the suicide rate so low at Foxconn.

Foxconn is a chinese company that you may have heard a lot about recently. There has, according to the BBC been "a string" of suicides there recently. According to the Times there is a "spiralling suicide crisis". Reuters says there has been "a spate of employee deaths".

10 people have committed suicide this year at a particular Foxconn factory in China (where a lot of parts for the iphone are made, apparently, which I think is why this is supposed to be a news story). The factory employs 300,000 people. I make that a suicide rate of (approximately) 7 people per 100,000 per year. The suicide rate in China is about 13 people per 100,000 per year. In other words, working for Foxconn cuts your chance of committing suicide almost in half!

How is it possible for every single person everywhere in the world's media to have gotten this story exactly backwards? There are a lot of very clever people suggesting "explanations" for the suicide rate at Foxconn. Unfortunately, they're trying to explain why it's so high, when they should be doing the opposite! This should lead us to seriously doubt these people's 'explanations' when the phenomena they're describing happen to be real. If your theory can explain anything, it has no explanatory power at all.

However, I think the main story here is how this became a story. What is going on? Why did someone decide to report the suicide rate at Foxconn instead of, say, the suicide rate among Tesco employees (another company which employs around 300,000 people, at least in the UK). And how did no-one notice that what they were reporting was in no way interesting.

Deadweight Loss

I'm currently reading Joel Waldfogel's book "Scroogenomics". In it, he expands on some of the points made in his classic research paper "The Deadweight Loss of Christmas". The basic premise is that people (especially distant relatives) don't know what you want as well as you do, so any gifts they buy you are less desirable to you than anything you could have bought yourself with the money. He has plenty of facts and figures to back up this eminently plausible theory, and I think a serious point to make.

However, he does have at least one minor slip. In describing what deadweight loss is, he says the following:

If a dollar disappears from my pocket and appears in yours, it's a loss to me, but it's not a deadweight loss to society. If you take my dollar and destroy it lightling your Cohiba, then it's a deadweight loss.

This isn't quite right, for the simple reason that dollars only have purely symbolic value. Burning a dollar bill is a genuine loss of $1 to the burner, but can't possibly make society as a whole worse off... you can't eat money. So who benefits? As the wikipedia article on burning money explains, everyone. Burning a banknote has a (very) slightly deflationary effect, so makes all of the money in everyone else's pocket worth slightly more.

I first encountered this idea in Steve Lansburg's excellent Armchair economist, and it seems to be pretty standard fayre in economics literature, so how did Waldfogel miss it? Or did he think that burning money seemed more wasteful than any other genuine example of a deadweight loss, so sacrificed accuracy for impact?

What exactly are confidence intervals?

So, a friend (who would probably prefer to remain nameless) is currently looking for jobs in finance, and sent me some sample interview questions that they like to ask people. One of them is the following:

A drug trial gives the result that the drug works better than the
placebo, with 95% confidence. What exactly does this statement mean? What further assumptions are needed to be able to deduce that the probability of the drug working is actually 95%?

Now, I wasn't entirely sure I knew the answer to this question. I thought I did, but despite having studied rather a lot of statistics, I don't think anyone ever actually told me what a 95% confidence interval was, so I did what everyone does faced with such a situation, and checked the wikipedia article. Wikipedia is singularly confusing on the matter, but it gives the answer as roughly the following.

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