david's blog

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.

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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.

It's cherry-picking time: more poorly reported science being peddled to journalists

Yesterday the Daily Mail trumpeted “For every hour of screen time, the risk of family life being disrupted and children having poorer emotional wellbeing may be doubled”, while the Daily Telegraph said that "for every hour each day a child spent in front of a screen, the chance of becoming depressed, anxious or being bullied rose by up to 100 per cent”.

More deaths due to climate change? Or maybe not.

Coverage of a paper just published by Journal of Epidemiology and Community Health included dramatic headlines such as the Guardian's Heat-related deaths in the UK will rise 257% by 2050 because of climate change. But a closer look at the numbers in the paper paints a rather different picture.

How surprising was the cluster of cycle deaths in London?

More or Less recently featured Jody Aberdein talking about the cluster of 6 cycle deaths in London over a 2 week period.

The paper with the details of the analysis can, for a while, be freely obtained from Significance magazine.

PISA statistical methods - more detailed comments

In the Radio 4 documentary PISA - Global Education Tables Tested, broadcast on November 25th, a comment is made that the statistical issues are a bit complex to go into.

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