The overall benefit for APS students was six points, the equivalent of three As in the private sector, as against three Bs in state schools. But when general studies was excluded from the calculation, the overall benefit was less: three As to one grade A and two Bs.
But researchers pointed out that general studies was not rated as highly By higher-status universities as an entry qualification in the same way as are other A-levels, so APS students could have an advantage in obtaining places.
The study, the first of its kind, was carried out by the Centre for Educational Research at the London School of Economics. It aimed to assess how far independent schools provided added value above what could be achieved in the state sector.
The scheme was set up in 1981 by the Conservatives to help bright children from low-income families, but was abolished by the incoming Labour Government earlier this year.
Researchers looked at 393 pupils, 59 of whom had been offered an assisted place, but rejected it and had taken A-levels in state schools. One-third were female. The verbal reasoning test scores between the APS and state-educated pupils were not significantly different on entry, so researchers said there were good grounds for believing that the two samples were similar in ability.
But Anne West and Robert West, the authors of the report, published in Educational Studies, sounded a warning note, pointing to the relatively small sample.
"In addition, it is possible that the sample of schools that were able to provide us with information about the background characteristics of pupils who had been offered places were not representative of schools that are part of the APS."
Researchers were also unable to explain why there was the difference in performance. It could be higher expenditure, smaller classes, better quality education; or it could be attributed to family backgrounds and parental pressure.
More than half of all Labour voters support the Assisted Places Scheme, says a MORI poll commissioned by the Independent Schools Information Service.
Just over half the sample of nearly 2,000 parents said they would send their children to independent schools if they could afford it. This was the first time in five years of the ISIS annual survey that the figure exceeded 50 per cent.
Educational Studies, Vol 23, Number 2, July 1997, Carfax Publishing Ltd, PO Box 25, Abingdon, Oxfordshire, OX14 3UE.