September 2011 Archives

Penney's Game puzzle

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Penney's Game is a non-transitive probability game involving coin tosses. You invite your friend to name a sequence of coin tosses (at least three long), and you can always name a sequence that is more likely to come up first.

See this link which suggests a card-game variant for a good explanation and a diagram.

Now, what happens if you have five players. Player 1 names HTT as his sequence. Player 2 names HHT in order to beat Player 1. Player 3 names THH to beat Player 1. So Player 4 names TTH to beat Player 3. Player 5 now names HTT to beat Player 4.

If Player 2 usually beats P1, P3 usually beats P2, and P4 usually beats P3, then how does P5 - equivalently P1 usually beat P4? P1 < P2 < P3 < P4 < P1 ??

Bit baffling at first, but I think it's fairly easy to figure out what I've partly neglected to point out.

All this comes from a discussion on the JREF forums of this vos Savant column - which prompts an entirely separate discussion of random strings and probability...

On academic publishing

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There's been substantial discussion lately over academic publishing. Most recently, George Monbiot put out this on Comment Is Free, to be followed by this response on the Scholarly Kitchen (a blog from the Society of Scholarly Publishers). I can't remember where I saw many other discussions of this - if you know any feel free to comment (edit: Ahah - the ever excellent Peter Coles had this blog).

Let me say first I find both a little aggressive in tone, but there's important points raised by Monbiot, and some sensible responses by Kent Anderson at the Scholarly Kitchen.

First off I do want to say that frequently individual article prices are absurd and I've often been put off dismantling what I suspect is very dodgy research because I'd have to pay some crazy price to read it (and I have access to most major journals through the subscriptions of my employers). I can't expect my employer to pay for it (or a more expensive full subscription) if it's outside my field and I'm just making some comment beyond the remit of my work. I end up just not looking.

Secondly, us physicists make great use of the arXiv, but that is much more expensive to run than people realise and it takes something like half a million dollars a year of public funding of various sources to support, and it does no peer review or any of the other functions publishers directly perform.

On to Anderson's post though. He argues early on that most papers are inaccessible to anyone but specialists anyway, because they're too technical. He searches PubMed for 'cardiac', picks the first paper and points out its unparseable to most people. The bit he quotes is 
Intrathoracic herniation of the liver ("liver-up") is associated with predominant left heart hypoplasia in left diaphragmatic hernia but not right fetal diaphragmatic hernia. Our observations indicate that this difference may result from different ductus venosus streaming sites in these conditions.
Now, I haven't done biology since double science at GCSE, but I broadly get the gist of 'intrathoracic herniation of the liver', 'predominant left heart hypoplasia', 'left diaphragmatic hernia' (and naturally the right version), although I'd have to Google ductus venosus streaming sites. I bet if I wanted to actually read this paper I'd have more clue about it, and there's no reason to think that a well-motivated reasonably intelligent amateur couldn't manage that. Admittedly I'm one person and a bit of an oddball in this sense but then...

... then there's the fact this is a randomly selected paper, and only one randomly selected paper. If I was trying to find out something about hearts, maybe my grandfather was started on some new medication I wanted to find out more about, I'd be doing a more detailed search, and even then if this cropped up I'd skip it in favour for something more obviously up my street. This single example of a mildly difficult to parse abstract is in no way an indication that most papers published are going to offer no value to people outside the immediate specialisation.

Anderson says
Let's assume I can read the whole paper. Like 99.9% of the population, I'm not going to know what to make of it.
Well over two million people in the UK have some kind of science, technology or engineering degree, and are probably going to be able to make a reasonable stab at parsing a lot of the essentials of a paper they are interested in. A not insignificant minority of these are going to have the skills in statistics to make reasonable criticisms of some papers from that angle without even knowing anything about a subject. If you gave a statistician a paper on a drugs trial they don't need to know anything about pharmaceuticals to critique the analysis. Many will be able to offer criticism of experimental design too.

This is particularly important for the kind of paper many will want to know about - e.g. a new cancer drug has come on the market and your mother has the cancer in question, and you want to know what justification the NHS has for saying it's not effective enough and they're not paying for it.

Anderson says
To chart a useful course forward, we need accurate information, rational thought, and reasonable plans. Monbiot provides none of these in his inflammatory, off-base, and ultimately unfair rant.
I find this a mildly baffling statement. Monbiot supplies quite a number of figures and accurate information, he certainly provides some rational thought (maybe not all though) and offers reasonable plans. I think Anderson is making something of an unfair rant himself.

There's a real absurdity in expecting certain private individuals (I can think of several excellent bloggers) to stump up tens of dollars for a single paper which they probably already think is a bit shit, or they wouldn't be wanting to download it to criticise it. And being able to criticise scientific publications is pretty crucial, even if you're not a specialist, especially when it has either been funded by public money or is about to lead to public money being spent.

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This page is an archive of entries from September 2011 listed from newest to oldest.

June 2011 is the previous archive.

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About the author

Edd works somewhere between astronomy and computing and has a general interest in science, skepticism and other related topics.

Opinions expressed in this blog are my own and not those of my employer.