Thank you for downloading this week's more or less podcast. Here's Tim Harford.

Hello and welcome to more or less. If numbers were food, we'd be ready steady cook.

This week we'll be whipping up a feast from the most unlikely ingredients.

War, bad science, bicycling, yes, again, and death.

It's 316 times more difficult to kill 10 times more people.

But first, amid this summer's political argument about public sector pensions

described as unaffordable by Nick Clegg, journalists began to quote life expectancy figures,

which is fair enough because the longer we live, the less affordable our pensions become.

I understand that there is an upside to living longer too.

The trouble is, there are several ways you can work out life expectancy, and over the years,

few have proved very reliable. Listen to Paul Sweating, wrote to us,

to query figures used in a BBC News online report.

It was an article I saw which was talking about the increase in pension age,

and talked about an increase in pension age from age 65 to 66, and then said the comparison,

the current life expectancy for men is 77, and it's 81 for women.

According to BBC News Online, a man retiring at 66 can expect a mere 11 years rest after

over 40 years of toil. But that's wrong, says Paul Sweating.

Who, when not listening to more or less, fills the lonely void by working at the University of Kent,

where it turns out he's professor of actual aerial science.

The number they quoted is what's called a period life expectancy from birth.

Say it was calculated using 2008 mortality data.

So what you would do, you would say, look at each age and see how many people there were of that

...