Bacon Sandwich

I'm pretty busy writing up my work at the moment, hence the long break in posting this month. I'll try to fire out a few short but useful entries over the coming weeks rather than saving it all up for the monolithic posts I usually make.

Every week, some newspaper or another makes us frightened or happy by covering the latest risk data regarding "causes" or "cures" for cancer, stroke, heart disease and the like. Apparently they won't be happy until they've fully catalogued all Things at least once over, and preferably twice with flatly contradictory information. They present us with statements such as "Bacon Sandwiches raise cancer risk by 20%". That would probably put quite a few people off eating bacon sandwiches, but it's not a statistic you'll ever find in a peer-reviewed scientific paper. And there's a good reason for that. This sort of figure is what is called a "relative risk increase". It's calculated by taking the dividing the new risk (with bacon sanswiches) by the normal risk (sans sandwich) and multiplying by 100. We can see the weakness of that way of representing the numbers with an illustration such as this:

The risk of killing yourself with a revolver loaded with only a single bullet in a random chamber is 1 in 6. Put two bullets into two random chambers and the risk is 2 in 6 (or 1 in 3). These are absolute risks as opposed to relative risks. In percentages, the absolute risk is just over 16% with one bullet, but twice that (32%) with two bullets. Now let's do a Daily Mail on it and express this as a relative risk increase. That's a 16% increase over 16%. So by putting in the extra bullet you've just increased your risk of killing yourself when you pull the trigger by 100%. That last number is certainly the scariest, although we must admit that none of these numbers is particularly fun.

But here's where it gets interesting (stop rolling your eyes please). Imagine the risk of catching a fatal dose of the flu is 1 in 10,000,000 for each time you go to work on the train, but is 2 in 10,000,000 if you take the bus. These odds are very much lower than the absolute risks relating to the gun. In percentage terms they sound comfortingly low too (0.00001% increasing to 0.00002%). You're probably not going to base your public transport decision making on these numbers. However when we convert these numbers into a relative risk increase, we get... 100%. A headline that says "Buses Raise Flu Death Risk by 100%" is certainly going to either make you think twice about using the bus, or is going to make you think that those silly boffins are just spoofing (didn't they say buses were better for some reason last week?). You get exactly the same punch in a Daily Mail headline as the gun risk, and yet in reality they're not even vaguely similar.

This week a nice site caught my eye which puts all of that statistical wonder into a fun little web program that allows you to see the various ways in which scientific data can be made more scary. There's all sorts of ways to make a scare story out of a non story, and you can rest assured that most of the newspapers are quite prepared to use them.

Image from Wikipedia released under the terms of the GNU Free Documentation License.

Holy F**king Sh*t: Daily Mail debunks MMR autism link

This post may be unsuitable for minors or people upset by scenes of total doublethink.

Well, the day has finally come. The Daily Mail has finally joined the rest of the world in accepting that MMR is safe, and that the 1998 study by Andrew Wakefield has been "debunked" (even though the study never says that MMR causes autism, a press release did and it was debunked 10 years ago). Measles is on the rise again, and that's actually a big deal. Kids are getting sick, people have died and someone is going to hang. This isn't just Wakefield's fault of course. No, he should not be a scapegoat! There are others to blame. Us, apparently. In a remarkable display of doublethink, the Daily Mail points the finger at "middle-class MMR refuseniks". Parents who somehow bought the press-release pseudoscience presented by Wakefield (minus the et al). They must have picked it up off Reuters, the wiley middle-class (yet strangely uncritical and credulous) bastards.

Of course, the Mail don't mention the media frenzy that followed the "confirmation" of Wakefield's 1998 work (by, er.. Wakefield). The evidence-free total bullshitstorm that presented Wakefield's speculations directly to that middle-(and working-) class audience as if it were yet another scientific "breakthrough". The torrent of jargon filled trash that published everything that vaguely supported the hypothesis but ignored the dozens and dozens of studies debunking it, milking that story for every millilitre of newspaper sales it had. And how could they, since up until a month ago the Daily Mail were still doing it? Still implying that MMR was dangerous. But today they've hit the reset button. And I feel like I just fell through the looking glass. It's funny, in a totally horrifying kind of way. Well, let me just say, so that we can be clear. And you'll have to forgive me for my profanity because it just feels like that sort of moment.

THIS WAS YOUR FUCKING FAULT, YOU MORONS.

I mean, seriously. Read your own articles. People are going to hang for this, but the media are the ones judging who, so the list will doubtlessly be restricted to:

-A. J Wakefield
-The Middle Classes

I feel like I'm taking crazy pills.

Update 18:08: It's even crazier than I thought. A search for "MMR" on the Daily Mail reveals a similar article in 2008 blaming "mothers" for the oncoming measles epidemic. This article sits amongst yet more panic pieces calling MMR "controversial" and cagey coverage of the research that 'disproves MMR jab link to autism' (the quotes were in the headline as if incredulous). Clearly, the Mail spent 2008 being eased into a gentle but enormous u-turn.

Things Happen After Event Shock

The Daily Mail have decided to have a go at MMR again as pointed out by Ben Goldacre at Bad Science. A child has fallen terribly ill "six months after MMR jab". Ten years after Andrew Wakefield speculated himself into the headlines by suggesting a link between MMR and autism (in a press-release mind, not in a research paper), this misguided rubbish is still being presented as "science news". Actually, most of the papers now seem to reject the link and are thus in the business of demonizing Wakefield himself, as if they had nothing to do with the scare. But the Daily Mail is apparently not quite ready to take even that ass-covering step. They cite the 1998 Wakefield paper (it was a press release that actually made the claims) and I have responded, though I wonder if it will be published.

Daily Mail, please read the 1998 paper by Wakefield et al. It does not suggest anything more than a temporal connection between the MMR vaccination and the onset of a symptom associated with autism (colitis) that's a long way from even suggesting a possible connection between MMR and autism. Wakefield decided to make that particular suggestion directly to the press, perhaps because the evidence did not support him and he knew it would not be published. More tellingly, ten of his his co-authors on the 1998 paper retracted their support for that claim.
So here we have another temporal association. Thing Y has happened after thing X. And so we must assume that X caused Y, right? Rubbish. I'd imagine a whole load of things happened before this poor kid fell ill.

At this point I ran out of words in the little submission box, so I'll conclude as I would have liked.

The child doubtlessly slept, ate breakfast and breathed constantly just prior to falling ill. So far as we can actually gather from the evidence here, almost anything could have "caused" this tragedy. The likeliest explanation though, is that it was nothing we could have predicted. You write that the child had previously suffered brain damage due to a Herpes Simplex infection at the age of two weeks. Anyone who has had coldsores will know that re-activation of that virus (it never leaves us) is not a predictable event and it has never been causally linked to events such as vaccination, as far as I'm aware.

To imply that MMR was responsible for this sad event is deeply irresponsible journalism and it will doubtlessly further the anti-vaccination movement and lead to more sick kids, and probably more deaths from measles- a disease that was nearly extinct in Europe before this totally unfounded scare.

Update 23 Jan 2009: Predictably enough, my comment has not appeared on the Daily Mail article. Nor have any at all, for that matter. Given that the Goldacre Evidence Army was alerted, that seems just a little suspect to me...