Find the UK's top schools

Confused? Most people are. You need a degree in statistics to make sense of this year’s secondary school league tables.

Originally the tables reported performance – the school that had the best GCSE results was at the top, the one with the worst at the bottom. Now we have a Contextual Value Added (CVA) score, which purports to measure how much progress students have made.

A simple value-added calculation that compares students’ achievements on entry to their exam results at 16 is a good idea. We need to know which schools are helping their students make most progress.

But this year’s CVA is far from simple. Factors such as the gender, ethnicity and social class of students are taken into account. Girls, for example, are thought to work harder than boys so a school’s CVA score is reduced by 14 points for every female student. Chinese and Indian students are considered to be the easiest to teach so 32 points are taken off for every Chinese and 24 for every Indian student.

Is it true that girls always work harder than boys? Nationally, the statistics may stack up, but individual students are not necessarily going to conform to the pattern. When it comes to comparing one school with another the CVA score needs to be treated with caution.

The key measure for any parent is the percentage of students who achieved five good GCSE grades including English and maths. Too many schools have chosen to bolster their league table position by entering their students for easier subjects such as media studies.

Ninety three per cent of students at Leigh City technology college in Kent, a flagship city academy, scored five A*-C GCSE grades. Just 24% managed five good grades including English and maths.

You might wonder, too, why top independent schools, such as Winchester college and St Paul’s, languish at the bottom of the tables. Not one student at these schools, it seems, achieved five good GCSE grades. In fact, both schools achieved 100%. The explanation is that these and many private schools, fed up with dumbed down GCSEs, enter their students for the tougher International GCSE. The government refuses to acknowledge the IGCSE.

The moral is obvious. Use the tables in thinking about the best school for your child, but use them carefully. When Ken Clarke was in charge of education he was asked how he could justify publishing raw GCSE scores when so much depended on a school’s intake. He said he would rather have data raw than cooked. He was right.

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