Welcome to Understanding Uncertainty

Welcome to the site that tries to make sense of chance, risk, luck, uncertainty and probability. Mathematics won't tell us what to do, but we think that understanding the numbers can help us deal with our own uncertainty and allow us to look critically at stories in the media.

The Norm Chronicles, By Michael Blastland and David Spiegelhalter, is now available for purchase! Some reviews are here, and here


'Tails you win: the science of chance' aired on BBC4 at 9pm on October 18th.

If you want to see where all the numbers came from in the programme, we've prepared a page of all the gory details.

Do you have a coincidence story? David Spiegelhalter is collecting them over at http://cambridgecoincidences.org.


Elsewhere on UnderstandingUncertainty:

Sub-editing in the Times

A story in monday's Times had the following dramatic headline:
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Is prostitution really worth £5.7 billion a year?

The EU has demanded rapid payment of £1.7 billion from the UK because our economy has done better than predicted, and some of this is due to the prostitution market now being considered as part of our National Accounts and contributing an extra £5.3 billion to GDP at 2009 prices, which is 0.35% of GDP, half that of agriculture. But is this a reasonable estimate?

Why 'life expectancy' is a misleading summary of survival

It's well-known how misleading it can be to use average (mean) as a summary measure of income: the distribution is very skew, and a few very rich people can hopelessly distort the mean. So median (the value halfway along the distribution) income is generally used, and this might fairly be described as the income of an average person, rather than the average income.

Using expected frequencies when teaching probability

The July 2014 Mathematics Programmes of Study: Key Stage 4 (GCSE) specifies under Probability

{calculate and interpret conditional probabilities through representation using expected frequencies with two-way tables, tree diagrams and Venn diagrams}.

- the brackets and bold case means this comes under additional mathematical content to be taught to more highly attaining pupils.

Another tragic cluster - but how surprised should we be?

Sadly another passenger plane crashed yesterday - the third in 8 days, the Air Algerie flight on July 24th, the TransAsia flight in Taiwan on July 23rd, and Malaysian Airlines in Ukraine on July 17th. Does this mean that flying is becoming more dangerous and we should keep off planes? The following analysis may appear cold-hearted, but is not intended to diminish the impact of this tragic loss on the people and families involved.

Using metrics to assess research quality

The Higher Education Funding Council for England (HEFCE) is carrying out an independent review of the role of metrics in research assessment, and are encouraging views. I have submitted a (very personal) response, using HEFCE's suggested headings, which is given below in a minimally-edited version.

++++++++++++++++++++++++++++++

Could a 'safest' option on sat navs save lives?

insert alternate text
by TobyJ

Since the start of our relationship my partner and I disagreed about the best way to travel the approximately hour long journey between our homes on either side of the peak district. She preferred the well lit M60 and M62 route, feeling that it is considerably safer. I preferred the Woodhead pass, the quicker route which winds its way over the hills, and was after all suggested by Google Maps.

Numbers and the common-sense bypass

Yesterday the Sunday Times [paywall] covered a talk Anne Johnson and I had given at the Cheltenham Science Festival about the statistics of sex, and the article said

more people are having sex in their teens, roughly 30% before the age of 16.

A heuristic for sorting science stories in the news

Dominic Lawson's article in the Sunday Times today[paywall] quotes me as having the rather cynical heuristic: "the very fact that a piece of health research appears in the papers indicates that it is nonsense." I stand by this, but after a bit more consideration I would like to suggest a slightly more refined version for dealing with science stories in the news, particularly medical ones.

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