Brian Clegg's Blog, page 57

Correlation, causality and accusations of witchcraft

A story in the news today was a classic example of the confusion of correlation and causality. Scientists are always banging on about this, and some people wonder how this apparent statistical nicety matters - yet it's the reason that over the centuries people have been accused of witchcraft.

Correlation is when two things happen in proximity - of time, space or both. Causality is when one causes the other. Because we understand the world through patterns, when there is correlation, we tend to assume causality - but without evidence, this is a mistake. In the case of witches, an old person might curse a farmer for not giving them some milk. Two days later, one of the farmer's cattle dies. Burn the witch!

You might think that we are beyond such thinking in the UK, but unless there is data that wasn't presented in this news story, we clearly aren't (I read it in the i newspaper, but I'm sure it was elsewhere too.) There has been a large rise in the number of students accessing counselling services in universities over the last few years. Over the same period, tuition fees have pretty much trebled. There's the correlation, but as yet we've no evidence (let alone proof of causality). So what are we given?

A spokesman from mental health charity Mind said tuition fees and student loan debt were 'major contributors' to the rise in students seeking mental health help. Evidence? None given - appears to be a pure assumption. He went onto say it was 'unlikely' that the rise reflected greater openness around mental health. But even if this is the case it doesn't mean there is only one other cause - it's not either/or.An NUS spokesperson said 'The evidence is clear - the marketisation of education is having a huge impact on students' mental health' - what evidence, except correlation. Pure political witch hunting statement.A psychologist commented 'Research has shown that financial difficulties, such as being unable to pay bills, has an impact on mental health in students.' Quite probably true, but totally irrelevant. Student loan repayments don't kick in until the end of the course when the student is earning over £21,000.Let's be clear, I'd prefer it if we didn't have tuition fees, and mental health issues are very important. But by leaping from correlation to causality in this way, the story totally undermines its argument. There may be evidence of causality - but it certainly isn't presented. If the psychologist is right, it seems far more likely that the cause (over and above more reporting) is financial difficulties while a student - which has nothing to do with tuition fees. But without data, to make this kind of suggestion is an irresponsible act.

Crikey! Where are my exclamation marks?

Apparently, the Department of Education has instructed moderators testing 7-year-olds' writing abilities to only consider a sentence with an exclamation mark correct if that sentence starts with 'How' or 'What' and uses 'the syntax of an exclamation.'

This is one of those ideas that come about with the best of intentions but totally miss the mark. Most young writers do use far too many exclamation marks. Of course, there are no such things as hard and fast rules in writing, but like swearing, exclamation marks are generally much more effective if used sparingly and pointedly. So I can absolutely understand an urge to cut down on exclamation mark confetti.

However, there are two big problems here - the age and the criteria. Whether or not you approve of testing 7-year-olds (I can see a point of doing it as a benchmark), it sounds too young to pin down punctuation. Far worse, though, are those criteria.

Along with almost everyone writing since 1920, I would hardly ever use an exclamation mark in a sentence beginning 'How' or 'What'. I just don't feel the urge to write 'How do you do!' or 'What ho, Jeeves!' Checking the nearest English usage guide (Swan, Practical English Usage), there are some sensible examples for how and what, but Swan also points out that these are often formal or old fashioned, such as 'How nice!' or 'What a rude man!' And he lists various other common forms of acceptable exclamation, such as so/such sentences and negative questions ('Isn't it beautiful!')

As for 'the syntax of an exclamation'? What is that all about? Really. I have no clue what they mean. And I'm supposed to be a writer.

It's stupid!

Chancellor for President

Like most of us who think having a royal family is a waste of public money and newspaper column inches, I get regular 'Yes, but what about...' retorts. Some of them are just inane, such as 'They bring in a lot of tourism.' Really? So France really has trouble getting visitors ever since they got rid of their royal family?

Clearly this can't be about people actually seeing the royals - very few visitors, for instance, will see Prince William on the(mostly closed to the public) two days of work he manages to squeeze into a week. If there is any draw, it's about the pageantry and the royal palaces. Well, guess what? We can still change the guard and all that stuff - in fact if we really wanted to save money, we could even do it with cheap unemployed actors, rather than wasting our military's time. And all of the royal palaces could be open all year round, rather than bits of them at times the royals fancy it. Oh, and there'd be a lot more public access in the Duchy of Cornwall.

As an argument, that's a busted flush. But I confess I've struggled in the past with the 'Yes, but if you have a president you'll just end up with another bloody politician as head of state,' argument. And what's going on in the USA, entertaining though it may be, is no encouragement. But I realised today what the model should be - university chancellors. They are the equivalent of a formal head of state, leaving the actual running of the university to the professional vice chancellor - and with a few oddities, the chancellors are excellent at their jobs. So let's model the British president on a university chancellor.

I don't know, to be honest, how they end up with such good choices, but here's one suggestion for how to do it. You would be barred from office if you had ever been a politician or civil servant. Each major party could put forward one candidate, plus a single public candidate, where anyone could put themselves forward for an online vote.

As always, there's fine tuning - come on, I thought of this on the train to Bristol. But you know it makes sense...

How far away is that ancient galaxy?

Credit: NASA, ESA and P. Oesch (Yale University) The news has been full of the remarkable discovery of galaxy GN-z11, which appears to have formed just 400 million years after the origins of the universe. Definitely 'A long time ago, in a galaxy far, far away.' But exactly how far? Unfortunately some of those reporting the news have been a little confused on the distance to the galaxy.



What do we actually know? We are seeing GN-z11 as it was around 400 million years after the Big Bang - so the light has taken 13.4 billion years to reach us. And it was discovered with a redshift of around z=11.1. (You can read the actual paper here.) That 'z' value represents the difference between the observed wavelength and the emitted wavelength divided by the emitted wavelength, so z=0 would mean there was no red shift at all.

Unfortunately, some of those reporting this went a step too far with headlines like this:

Here's a few more iffy remarks:'GN-z11 is a record-breaking 13.4 billion light years away...''Located a record 13.4 billion light years from Earth...''NASA's Hubble Space Telescope has discovered the most remote galaxy ever seen from Earth - 13.4 billion light years away.''A galaxy 13.4 billion light years away has been spotted by the Hubble Space Telecope.'It seems a reasonable idea. We've heard that the light has taken 13.4 billion years to reach us - so surely the galaxy is 13.4 billion light years away? Unfortunately, no - because the universe has not been sitting around doing nothing for the last 13.4 billion years. The point of that 11.1 value for z is that this galaxy is seriously red shifted, which means it is moving away from us at a heck of pace. While the light has been on its way, the universe has expanded massively, so this ancient galaxy is now far more than 13.4 billion light years away.

How far away? We don't know for certain. The calculation is messy. Luckily Edward Wright of UCLA has produced a calculator that will give us a feel for just how far away the galaxy is. The bad news is that there are several factors that have to be entered into the calculator, including an assumption about the nature of the curvature of the universe, Hubble's constant, which relates the redshift to the distance, and the proportion of matter and dark energy - the more dark energy, the faster the acceleration of the expansion. (I slightly over-simplify the model, but that's a fair picture.)

Plugging in what seem to be the best accepted current values into the calculator comes up with an approximate 'comoving radial distance', the most meaningful measure to call the distance to the galaxy, of around 31.8 billion light years - rather more than 13.4. Far, far away indeed.

Unweaving the rainbow of news

I've often moaned about the poor use of statistics in the news. Today it's more a case of a total absence of stats, which could have put a story into context and would have made it more informative.

In the story shown, we learn that 'everyone says it's incredible' that a mother born on Feb 29 should have a child also born on leap year day.

But if the journo could have just taken a moment to think, he or she could have put this into useful context. It certainly seems incredible if you misapply statistics and think there's a 1 in 1,461 chance of the mother being born on Feb 29, and similarly for a totally randomly occurring baby, making it a 1 in 2.13 million  chance of the double. But that's just wrong because it's telling us about the chances of a randomly picked baby being in this situation, not the chances of the situation occurring this Feb 29th.

About 700,000 babies will be born in the UK this year, so with a 1 in 1,461 chance of the mother being born on Feb 29th, around 479 of this year's babies should be born to leap year day mothers. Of these, we'd expect one or two to be born on Feb 29th. Not that remarkable, then. (In practice things are a little more complex, as more babies are born at certain times, etc., but it's roughly right.)

There is always the 'unweaving the rainbow' argument aimed at Newton. Those who take this position argue that the facts get in the way of the poetry of the story. But I would argue it's possible to still find the story interesting, while being better informed by the context. Journalists would never tell us a political story without context - it's a shame (possibly because they don't know how to) that they ignore it in a statistical story.

A popular science blooper that stands on the shoulders of giants

Every book I've ever read contains errors. Mine certainly do. But recently I came across a statement in a popular science book that was so outrageously incorrect that I read it three times, because I was sure I was missing something. I wasn't. Here it is, in all its glory:


Let’s be clear. This was not some self-published diatribe by an individual who thinks that Einstein was a fraud and Tesla was an alien. It was written by a scientist (admittedly from the biological sciences) with considerable experience of science communication. And it was produced by a significant mainstream publisher with all the panoply of editing and proof reading processes that occur before reaching this final copy.

If you are of an arts-oriented bent, you might be wondering what the fuss is about. It’s as if someone wrote that Botticelli painted Guernica, that Bach wrote The Rite of Spring and that Shakespeare wrote War and Peace, all rolled into one. It’s not for nothing the C. P. Snow used the Second Law of Thermodynamics as his prime example of the relative ignorance of the arts world of science in his famous Two Cultures lecture at the end of the 1950s:

A good many times I have been present at gatherings of people who, by the standards of the traditional culture, are thought highly educated and who have with considerable gusto been expressing their incredulity at the illiteracy of scientists. Once or twice I have been provoked and have asked the company how many of them could describe the Second Law of Thermodynamics. The response was cold: it was also negative. Yet I was asking something which is the scientific equivalent of: Have you read a work of Shakespeare’s?

In case you are in any doubt, Newton did indeed have a second law - of motion, which in its modern form is the equivalent of saying that force is equal to mass times acceleration. It had nothing to do with thermodynamics, which, as the name, suggests began as a study of the way that heat moves from place to place, a solidly 19th/20th century science that started as a way of improving steam engines and ended up being one of the central aspects of our understanding of physics. The names that should be attached to it are the likes of Sadi Carnot and Rudolf Clausius, who respectively laid the groundwork and effectively first expressed the law, and Ludwig Boltzmann, whose statistical version made it far, far more than had first been intended.

I’m not going to name the author, book, or publisher responsible for the blooper. As I mentioned at the start, every book I’ve ever read has mistakes in it. But they are typically typos or silly memory errors. This (which is repeated later) is so fundamental that the mind truly boggles. I read it. I re-read it. I tried to find some way it could be ironic or some such clever thing.

But I couldn’t.

Diagram delights

It's time for my favourite book prize of the year. Forget the Booker. Ignore the Nobel. This is the Diagram Prize for the oddest book title of the year.

The shortlist has been published and it's a strong list indeed. So rather than say any more, I'm just going to let you relish those titles.
Reading the Liver: Papyrological Texts on Ancient Greek Extispicy (Mohr Siebeck) Too Naked for the Nazis (Fantom Films) by Alan StaffordPaper Folding with Children (Floris Books) by Alice HorneckeTransvestite Vampire Biker Nuns from Outer Space: A Consideration of Cult Film (MKH Imprint) by Mark Kirwan-HayhoeBehind the Binoculars: Interviews with Acclaimed Birdwatchers (Pelagic Publishing) by Mark Avery and Keith BettonSoviet Bus Stops (Fuel) by Christopher HerwigReading from Behind: A Cultural History of the Anus (Zed Books) by Jonathan Allan If I have a personal favourite, it would be the Biker Nuns, except this is clearly constructed specifically to be bizarre, so I rather incline (so to speak) to Reading from Behind.

You can find out more at the prize's administrative home, The Bookseller.

How long is a piece of string?

String theory is something that I've been highly sceptical about for some time, influenced by books like Not Even Wrong and The Trouble with Physics . This meant that a recent book, Why String Theory? by Joseph Conlon has proved a very interesting read to provide an explanation for the popularity of string theory among physicists, despite its apparent inability to make predictions about the real world.

I can't say the new book has won me over (and I ought to stress that, like Not Even Wrong, it's not an easy read), but what I do now understand is the puzzle many onlookers face as to how physicists can end up in what appears to be such an abstruse and disconnected mathematical world to be able to insist with a straight face and counter to all observation that we need at least 10 and probably 11 dimensions to make the universe work.
It seems that string theory emerged from an attempt to explain the strong force back in the late sixties, early seventies. The idea of particles as tiny strings, rather than point particles, seemed to provide an explanation for the strong force, however the only way to make it work required the universe to have 26 dimensions (25 spatial, one of time). This was all looking quite good (if weird, but quantum theory has showed us that weird is okay), until the new collider experiments showed the sort of scattering you'd expect from particles, not strings - and along came quantum chromodynamics, requiring only the standard 4 dimensions, blowing string theory out of the water.
However, the more mathematically-driven physicists loved string theory because it was elegant and seemed to hold together unnaturally well, even if it didn't match the real world. They continued to play around with it and eventually massaged it from what was intended as a description of the strong interaction into a mechanism for quantum gravity (or more precisely several mathematical mechanisms). The good news was that this did away with the 26 dimensions, though the bad news was it still required at least 10. Again, there was no experimental justification for the mathematics, but in its new form, mathematical things started to click into place. There was a surprising effectiveness and fit to other mathematical structures. The approach even fitted a number of oddities of the observed particle families. So the abstruse mathematics felt right - and that, essentially is why so many theoretical physicists have clung onto string theory even though it has yet to make new experimentally verifiable predictions, and has so many possible outcomes and all the other problems those books identify with it.
What Why String Theory? isn't very good at, is giving a feel for what is going on in the brains of the physicists in the way ordinary folk can understand (the author is himself a theoretical physicist), so I thought it might be useful to share an analogy that seemed to fit well for me. We're going to do a thought experiment featuring a civilisation that does mathematics to base 5, rather than the familiar base 10. So they count 1, 2, 3, 4, 10, 11, 12, 13, 14, 20, 21... For some obscure reason they use the same numbers as us, but only have 0, 1, 2, 3 and 4. Now these people have come across some textbooks from our civilisation. And they see all those numbers, which make a kind of sense, except there's some weird extra symbols.
Before I go into what they do, I ought to defend the base 5 idea, in case you're wondering why any civilisation would not sensibly realise they could count on the digits of both hands, but rather stuck to the 5 fingers and a thumb of a single hand. This isn't because the civilisation has a strange one armed mutation, it's because they were cleverer than us. How many can you count to on your two hands? Ten. But my civilisation can count to 30. This is because they don't regard their left and right hands as equivalent, but as two totally separate things with different names. The left hand has five digits. But the right hand has five handits. (Bear with me.) When they count on their fingers, they go up the digits of the left hand just as we do. But when the pinkie goes up, they close the whole left hand and raise the pinkie of their right hand, representing five. They then count up on the left again, but when they get a full hand they raise the second finger on their right hand, and so on. Instead of just working linearly across their fingers and thumbs, by working to base 5 their hands become a simple abacus.
So, back to interpreting our base 10 documents. Some rather wacky mathematicians in this society start playing with using bigger bases than base 5. There's no reason why, no application. It's just interesting. And when they happen on base 10 - so they're counting 1, 2, 3, 4, A, B, C, D, E, 10, 11, 12, 13, 14, 1A, 1B... they get a strange frisson of excitement. This isn't the same as the system used in our documents, where the 12th character in the list is 7, rather than C. But suddenly the two kinds of mathematics start to align. Calculations that didn't make any sense suddenly start to click.
In a hugely simplified analogy, this seems a bit like the string lovers' reason for sticking with their theory. It has that same kind of neat mathematical fit. It seems to work too well to be just coincidence. All those extra dimensions and intricate mathematical manipulation don't seem natural, any more than working to base 10 seems natural when you think of left and right hands as totally different things. But it doesn't mean there's not something behind it. I hope the analogy helps you - it certainly helped me to devise it!

How low can you go?

I support a number of charities, but like many people I have been appalled by the way that some of these organisations have not realised that in encouraging people to do the decent thing and help others, they also need to treat their donors decently, rather than considering them idiots to be manipulated and squeezed out of every last drop of cash. It's a very unpleasant case of 'the end justifies the means' - and as usual, this is a motto that doesn't hold up well to scrutiny.

The reason I bring this up is I've just come across the most cynical and unpleasant attempt to manipulate I've ever seen. I thought certain charities that send unrequested gifts like pens and mats in the hope of guilt tripping the recipient into paying were bad. But this is a new low.

Along with an apparent handwritten Post-it note - always a sign of dubious marketing - the letter from this charity, World Villages for Children had attached to it 12p. Twelve pence as cash. Actual money. They sent potential donors money. Why would they possibly do this? The letter from the charity explains that the author, Sister Michaela - the director of the charity, is sending me this 12p because she is desperate. What she wants me to do is send the 12p back to her, along with a cheque for at least £10 to help starving children in Guatemala. (If I do, apparently she will send me a bag containing six little 'worry dolls'.)

This is not a reason for sending 12p to me. There is only one possible reason - it is a marketing ploy. We all get junk mail that goes straight in the bin. But it is very hard to throw cash away. Especially cash that has been given to you by a charity. And for that matter, it feels evil just to put it in your pocket. Not to respond makes you feel guilty. It is top class manipulation.

Unfortunately, I don't like being manipulated. It's why I wouldn't watch the likes of the The X Factor or Britain's Got Talent, with their endless audience manipulation tricks. And it's why I'm not going to do what's intended of me here. I won't be sending that 12p back to them - I will be putting it in the collecting box of a charity that I support, such as the British Heart Foundation or The Children's Society.

I don't like to be repetitive, but I can't think of another adjective than cynical that so well describes this type of marketing.

*UPDATE* - Thanks to David Buick for pointing out that this approach has been going on for at least 10 years from this discussion.

Please note, if you comment, do not make any remarks suggesting that this charity's mailing is illegal or attempting to do anything illegal, as such comments would have to be removed as they would make this blog post liable to a takedown order, a mechanism often employed by those using this kind of marketing (see this post for details). The charity's methods are legal. But they are not acceptable.

You should never go back

Image from WikipediaGenerally speaking, I find the motto 'never go back once you've moved on' a helpful one. Although I've broken it pretty regularly, I usually find I shouldn't have attended that school reunion or whatever. However, it's a lesson that TV and filmmakers rarely consider, as I've been discovering with the new X-Files.

I was looking forward to the rebooted series after a 15 year break. The timing could not have been better. We got through the last DVD of the complete box set the same week the first episode arrived on a UK channel. And it's okay. But there's something rather upsetting about it.

It's not just that David Duchovny looks really worldworn and tired. Or that Gillian Anderson looks emaciated and zoned out compared to her far better recent UK TV appearances. It just seems far too much like 'more of the same.' I wanted to wait until episode 3 to give a verdict, as it was written by the man who wrote my favourite episode ever, the season 3 'Jose Chung's "From Outer Space"', which is hilarious and mind-bogglingly twisted. Admittedly episode 3 did have some fun moments, notably Scully telling Mulder, as he played with his smartphone, that he ought to stay away from the internet. And it had a very neat twist in the plot, which I won't reveal. But both the script and the acting was like seeing someone who once was on top of their game going through the motions.

For years, I hoped that they would make a new series of my favourite TV show ever, Buffy the Vampire Slayer. But now I realise that it would be a mistake. The world moves on. So do stories and actors. I'll probably stick with X-Files for this season. But it's a bit like watching Bruce Forsyth in the latter years of Strictly. It's with as much a sense of sadness as pleasant familiarity.