FRESH evidence that standards are lower in local authorities with grammar schools than in those with comprehensives will be published in July.
New research by Professor David Jesson, of York University's centre for performance evaluation, will make uncomfortable reading for Labour, which has left parents to decide on the future of grammar schools - and introduced balloting arrangements which will almost certainly preserve selection.
Professor Jesson's work, which will be published in Parliamentary Brief, Parliament's in-house journal, shows that pupils in selective systems make less progress between the ages of 14 and 16 than those in comprehensive ones. "It is perfectly clear that in a system where there is selection, the general impact is to lower performance," he said.
He compared the 15 authorities with fully-selective systems such as Kent, Buckinghamshire and Lincolnshire with those which have only a few grammar schools, such as Essex, and those which are fuly comprehensive.
The study, involving all 520,000 of last year's GCSE candidates, updates an earlier one which was criticised this week by Professor Sig Prais of the National Institute of Economic and Social Research. Professor Prais said the Government statistics on which Professor Jesson based his work were flawed. He also argued that grammar schools added more value to very bright pupils between the ages of 14 and 16 than comprehensives.
While Professor Jesson accepts that the original statistics were unreliable, he says there is still no evidence that bright pupils do much better in grammar schools than in comprehensives.
His new study, he says, has ironed out the flaws in the statistics and still shows that the effect of grammars on all pupils is to depress standards.
"Surely it is more important to look at the system as a whole and ask where we can improve, rather than considering the impact on the brightest. The evidence is that large numbers of pupils could do better if they were not selected out of grammar schools."
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