When it comes to willfully ignorant fuckwittery, the Daily Mail has a long and undistinguished record. But wednesday’s front page in the Daily Telegraph gave it a run for its money. Get this quote.

“The (Met Office) was accused of using a scientific model based on “probability” rather than fact to forecast the spread of the volcanic ash cloud that made Europe a no-fly zone and ruined the plans of more than 2.5 million travellers in and out of Britain.”

My more hip and net-savvy chums tell me the response to this is something like <facepalm>. Heaven forfend! A model based on probability!

Now my knowledge of vulcanology is based wholly on the brilliant “Volcano Adventure”, which while a thrilling read and including all manner of excitement is, let me be clear, a children’s book. Likewise I know little of aeroplanes other than that they have not been designed to allow anyone taller than a 7 year old to sit comfortably in economy.

But I do know something about models and probability. The Telegraph is here giving a particularly good example of the media’s contempt for statistics. It’s all in that line contrasting probability with fact, as if we should only base things on the latter. There’s a whole bookshelf of philosophy on when something should be considered a fact, but we don’t have time to deal with that.

Imagine you are crossing a busy road. You look around and see a car coming towards you. Do you know how fast the car is going? No, although you can guess. Do you know that if it hits you it will cause injury? Yes. However you intuitively estimate the probability that you can make it across the road safely.

Now in very informal terms, that is the same thing as the models we would use to assess the risk of flying. Only in the case of flights and volcanoes, it’s more complicated. Rather than just guessing (probably quite accurately) the speed of the car, we need to estimate the density of ash, and the effect it will have on the engines of aircraft. And we might want to err on the side of caution. But when it comes down to it, it’s the same thing. You use the best guess about the risk to say whether it is safe.

It is in fact very easy to see why, based on the facts, governments halted flights. Fact one: volcanic ash can damage aeroplane engines, and cause them to fall out of the sky. Fact two:  there has been volcanic ash in the sky over the UK. Does it follow from this that planes will fall out of the sky if they try to fly? Of course not. The sky is a big place, and we don’t necessarily know exactly whether the ash is. Meteorologists can help tell us where it is most likely to be, but that’s not a fact in the way the telegraph seems to be demanding.  In the absence of monitoring devices suspended all over the north west atlantic we have to estimate using some kind of model. And with that estimate comes probability.

Our friend Simon Jenkins has already weighed in with his considered and informed opinion that the ash based disruption is like swine flu.  And in today’s Guardian comment pages, Jenkins turns the Telegraph’s complaint around and carries on using it to beat the scientists. “The science offered absolutes rather than probabilities “. Talk about damned if you do and damned if you don’t.

However the most distressing thing about this is not the way an ignorant bunch of morons are stirring a story (think about it, that front page must have passed under the eyes of supposedly educated people). It’s the misuse of probability. Jenkins is concerned that a low probability is being treated as a high one, ie that it was always desperately unlikely that any plane would experience any untoward consequences. This however ignores uncertainty. If you are pretty sure that it is safe, but you think there might be a one in a thousand chance you are wrong, well you should pay attention to that. Just so you don’t think that I disagree with Jenkins about everything, I happen to think much of his analysis of the risk due to terrorism, and the abuse of civil liberties in response to it, is spot on.

The Telegraph meanwhile seems to think that if anything is expressed as a probability, then it can safely be ignored as not being a ‘fact’. This is the kind of ignorant garbage that condemns Darwinism as ‘just’ a theory, or exploits uncertainty about the rate and magnitude of climate change to justify political opinions which, in a remarkable coincidence, just happen to be exactly the same as those people would hold in the absence of any evidence about climate change at all. Both are the equivalent of stepping out into the road blindfolded.