3 August 2012 Last updated at 09:26 ET By Richard Knight BBC News

The mothers of US presidents and presidential candidates live far longer than the mothers of British prime ministers and opposition leaders. Is that just a statistical quirk?

Recreational statistics might not sound like your idea of fun but fiddling with numbers can yield fascinating discoveries.

Mike Shearing, a More or Less listener in Malaysia, thought he was on to something when he noticed that the mothers of post-war US presidents seem, on the whole, to have lived very long lives - much longer than the mums of British prime ministers.

He contacted More or Less to ask whether he had found something significant. The short answer is that he had. More or Less collated the age of death for every mother of a post-war US president or losing presidential candidate - except those who're still alive, of course - and for the mothers of every post-war British prime minister and losing opposition leader.

We analysed the data with the help of Dr George Leeson from Oxford University's Institute of Ageing.

"If we look at the US mothers we have an average age at death equal to 83.7 years," says Leeson, "and if we look at the UK mothers we have an average age at death of 74.8."

That's a big difference. Averages can be misleading, however, because a small number of outliers - or extreme measurements - can distort the picture. Rose Kennedy, for example, lived to 104. So Dr Leeson calculated the median figures, too.

"The median divides the data into two equal halves," he says, "so 50% of the observations are higher than the median, and 50% are lower. And the median is therefore less sensitive to outliers. The median for the US mothers is 84.5 - so very close to the average. For the UK mothers the average was almost 75, and the median is 76. So there's very little difference. It's not outliers."

Listen to More or Less on BBC Radio 4 and the World Service, or download the free podcast

Visit link:
The longevity of US presidents' mothers