Geoff Barton explains why the figures can’t always be trusted, while Jennie Golding shows her appreciation of symmetry.

If the league table results at your school are disappointing this year, have a whip round and buy this book for your headteacher. Then step back and listen for distant cheering.

The Tiger That Isn’t is a book about numbers and the way statistics can be used to tell dodgy stories; or a reminder, as Einstein put it, that “information is not knowledge”.

Like most public services, educationists get battered by targets, comparisons and performance tables. Surveys based on tiny samples hold a frequently unflattering mirror up to ourselves. Thus: A-levels getting easier; graduates can’t spell; exam students cheat via the internet; school behaviour out of control. And there are alluring statistics to back it all up.

For example, in January 2005 there was a familiar outbreak of moral panic about young people. Paper headlines read: “Yob Britain! 1 in 4 boys is a criminal”.

But when the two authors analyse the claim that 25 per cent of teenage boys are serious offenders, they unearth the survey’s key question: “Have you ever used force or violence on someone on purpose, for example by scratching, hitting, kicking or throwing things?” To which it adds: “Please include your family and people you know as well as strangers.”

So 85 per cent of the so-called assaults prove to be “pushing or grabbing”; 36 per cent are against siblings. So someone who shoves his brother becomes a prolific offender.

They similarly stick the boot into high government spending boasts, international comparisons and, deliciously, school league tables. “Make comparison too blithely and we turn information into a lottery,” they warn us. They debunk the comparison of the escape rate from British open prisons with those in Finland. Our figures, naturally, are dire, with inmates appearing to use prisons as luxury hotels while a remarkable 0 per cent of Finnish prisoners ever escape. How do the Finns achieve such excellence? “Because they are open prisons,” explains the Finnish expert, “we don’t call it escape, we classify it as absent without leave”. Thus a statistic crumbles before us.

The Tiger That Isn’t is not a book designed to make us feel good about ourselves; it isn’t saying that surveys, targets or published data are in themselves a bad thing. It simply takes issue with the relentlessly lazy way in which much public data is generated and (not) analysed. The result is a book that is both illuminating and highly entertaining.

Geoff Barton is head of King Edward VI School in Suffolk