Wednesday, 23 June 2010

Bridge Probability

I've been re-reading Victor Mollo's classic bridge book 'Card Play Technique: the art of being lucky'. I've come, once again, to the sections about probabilities that I just can't get my head round. Consider the following passage:
If the Ace of Clubs is right, all is well. If not, the contract will depend on guessing the diamonds. How then, should we set about it? The man in the street will draw trumps quickly, sway in his chair slowly and mutter something like: "Well, it's six of one and half a dozen of the other".
But is it?
To the expert there is a vital difference between the Club and the Diamond positions. The latter will be the subject of guesswork. The former lends itslef only to prayer. The Club must be played first, and the reason is that it will provide a clue to the Diamonds.
If East has the Ace of Clubs, West will be credited with the Ace of Diamonds.
There is similar reasoning throughout the book, just one hand later:
West has pleaded guilty to 7 points hearts and to the King of Diamonds: 10 in total. East has only 3. It is more likely that the defender's high-card strength will be divided between them 10-5 than 12-3. Therefore the best chance is to play East for the King of Clubs.
I just can't believe that this reasoning is valid. The deck doesn't know which cards we assign points to, so it is no more likely to put the Ace of Clubs in a different hand to the Ace of Diamonds than it is to put, say, the Three of Clubs in a different hand to the Ace of Diamonds. Similarly, while it is true that a 10-5 distribution is more likely, a priori, than a 12-3 distribution, surely this ceases to be the case when you've alread placed the remaining points 10-3 (assuming that the principle of Vacant Spaces doesn't come into play - ie, every player has followed with a small card to each of his partner's honours).

To repeat: the deck doesn't know which cards we assign points to!

Maybe this sort of reasoning is a useful shortcut to some valid reasoning, or maybe I'm missing something (I certainly hope so). Can anyone shed any light?

Tuesday, 22 June 2010

What's wrong with "sell"?

There are a *lot* of adverts on the TV right now for services like MazumaMobile, mobilephoneXchange and various others. There is also CashMyGold and PostalGold and no doubt many others. These are all companies to which you can sell your goods. The one thing that all of their adverts have in common (apart from being insanely annoying) is that none of them use the word "sell". I really can't understand why.

The most commonly used wording seems to be informing people that they can "exchange" their goods for cash. We already have a perfectly good word which means almost exactly "exchange for cash". Why don't these adverts use it? Because it would remind people that there are various other routes through which they could sell their gold/old phone/whatever? Because the word "sell" is unsavoury?

NB - Mazuma goes even further, suggesting that they can 'magic' your phone into cash... imagine that!

Monday, 21 June 2010

Whacky Formula: The Happiest Day of the Year

You might think that all the Irish people you saw smiling last Friday were just experiencing some good old-fashioned Schadenfreude at the abysmal perfomance of the England football team, but no, they'd probably been reading the Examiner. If they had, they'd've found out that Dr. Cliff Arnall has some 'research' explaining why June 18 is the happiest day of the year. He has a formula, in fact, for telling us exactly how happy every day of the year is.
The ex-Cardiff University lecturer’s complicated formula is: O + (N x S) + Cpm/T + He.
My, that does look complicated... what on earth could it all mean? Luckily there's an explanation for the formula in the article (although no explanation for why (N x S) is in brackets. You can read it below the fold.

Sunday, 20 June 2010

Pinker vs. Greenfield: is facebook rotting your brain?

I read two articles in the last week by leading intellectuals about what effect mass media have on the brain. One of them was Steven Pinker: Mind Over Mass Media. Pinker's conclusion:
The new media have caught on for a reason. Knowledge is increasing exponentially; human brainpower and waking hours are not. Fortunately, the Internet and information technologies are helping us manage, search and retrieve our collective intellectual output at different scales, from Twitter and previews to e-books and online encyclopedias. Far from making us stupid, these technologies are the only things that will keep us smart.
In a fairly scholarly article for Edge, Pinker cites evidence from cognitive science, psychology and neuroscience. He explains the bias that causes people to believe that mass media is damaging our brains:
As with primitive peoples who believe that eating fierce animals will make them fierce, they assume that watching quick cuts in rock videos turns your mental life into quick cuts or that reading bullet points and Twitter postings turns your thoughts into bullet points and Twitter postings
He pithily ridicules the notion that "changing our brains" is a bad thing:
Yes, every time we learn a fact or skill the wiring of the brain changes; it's not as if the information is stored in the pancreas
The other article I read was an interview with Baroness Greenfield, with the headline Facebook Addicts Can't Relate, Greenfield is worried about the effect social media is having on a generation that is growing up with it as a regular means of communication:
If you are not rehearsing looking someone in the eye in three dimensions, but instead you have 900 friends on Facebook ... one does question what kind of relationship they might be having,
In defence of her position that facebook might be contributing to rising levels of ADD (how can a diagnosis that didn't exist 30 years ago be rising?) she cites... erm... some studies that haven't actually been done:
Perhaps it's mandating a shorter attention span. I'm not saying it is but I'm saying, 'Wouldn't it be worth exploring?'
Of course it would be worth exploring.. but what is the point in encouraging sensationalist and uninformed scare stories in the press until it has been explored? She also warns us (somewhat ungrammatically) to be careful before we ignore her non-argument:
We are being complacent in the extreme if you just dismiss me as a whingeing, middle-aged Luddite.
Indeed... I'm not quite sure on what planet 59 qualifies as 'middle-aged' (the average age is still less than 80). But she's right, it would be silly to dismiss her fears because of her age, or her lack of fluency with the relevant technology. Dismissing them because they have absolutely no evidence to support them on the other hand...

I'll let you draw your own conclusions on which of the two articles I was most impressed by.

Friday, 18 June 2010

Reasons to be a Republican

Surely you can't give any sort of power, even figurehead-style can-only-use-it-in-an-emergency power to a guy who is capable of saying stuff like this:
Nature has been completely objectified — ‘She’ has become an ‘it’ — and we are persuaded to concentrate on the material aspect of reality that fits within Galileo’s scheme
“It is no good just fixing the pump and not the well,” he said. Talk of an “environmental crisis” or of a “financial crisis” was actually describing “the outward consequences of a deep, inner crisis of the soul”. 
Seriously. They guy picked Galileo as a general-purpose scapegoat for what's wrong with our world. Could he be less suitable to govern?

Thursday, 17 June 2010

Conjunction Fallacy

There's a sign that's just appeared in the changing rooms of Barts pool:
Please be aware that these areas are cleaned by male or female staff.
So not those hermaphrodite staff they use at Guy's and Thomas' then...

The "Forced to Deny" Files

The Metro settles the eternal question: is there life after death?. There is, and you can even be forced to deny things there....
Russell Crowe has been forced to deny that he's not dead
In other words 'someone said Russel Crowe was dead, they were wrong'. Gotta love 'forced to deny'.

HT (as they say) to @andydrizen

Wednesday, 16 June 2010

The wisdom to accept the things I cannot change

There are several 'life lessons' that I've picked up from playing bridge. Some of them are incredibly obvious in hindsight. Some of them less so. This is one of the more obvious in hindsight, but also one of the more important, so I think I'll start with it.

It is fairly common when playing bridge to reason thusly: in order to make this contract, I need West to hold the King of Diamonds. If West holds the King of Diamonds, then he can't hold the Ace of Spades. Therefore, I'll assume East holds the Ace of Spades and play accordingly (an example).

Tuesday, 15 June 2010

Blogging vs. Talking

There are several occasions when I've started writing a blog post about a story, realised halfway through that the point that I was trying to make was nonsense, and stopped. Note that if I was intending to write a blog post, this means that I had already thought about the issue for some fairly significant period of time. Somehow, writing it down allows me to see where I was going wrong.

I'm not sure if its writing things down, or just the process of articulating them that enables me to change my mind, however, I am fairly sure I change my mind about things less often in conversation than I do when writing blog posts about them. This can't be because I spend more time thinking about something before I say in than I do before I decide to blog about them: I write maybe 3 blog posts a week, I have several hundred conversations. I have a few explanations below the fold.

Monday, 14 June 2010

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?

Tuesday, 8 June 2010

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.

Wednesday, 2 June 2010

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.