I can highly recommend Marcus du Sautoy‘s video on the Guardian’s new Newton channel, exploring the world of chance and probability.

The good professor shows how probabilities become counter-intuitive as soon as a modicum of complexity is introduced. We all know that the chance of guessing heads on a coin-flip is one-in-two, and it’s fairly straightforward to show the chance of scooping the National Lottery jackpot is just under one in 14m.

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The prevalence of polling data presents a dilemma for news organisations – how to present it in a way their readers can best understand.

The Guardian’s handling of election polling data is a model of clarity and concision. It even includes information on the margin of error. The only additional feature I would like to see is a tool to translate the predicted share of the vote into Parliamentary seats. [Update – I hadn’t spotted this interactive Swingometer, which effectively does the same job] Read the rest of this entry »

Testing times

August 4, 2009

The rather worrying story that a quarter of 11-year-olds in England have failed to reach the expected standard in English and maths has been widely reported (Guardian here, for example) [link opens new window].

But when it comes to reporting the story, it is embarrassing to note that a common maths error has crept in, concerning the difference between a percentage increase and an increase in percentage points. My example is from the Liverpool Echo [new window] but as it’s agency copy, I’ve no doubt the story and its error are pretty widespread (although The Guardian’s report by Jessica Shepherd [new window] avoids the trap). Read the rest of this entry »