A study from Cardiff and Aberdeen universities of 60,000 students who went to university in 1992 found former independent school pupils were a fifth less likely to graduate with a first-class degree than those who went to a comprehensive.
Dr Bob McNabb, of Cardiff Business School, one of the authors, said: "Independent schools get their pupils better A-level results for their motivation and ability than state schools do. When everyone arrives at university, things change. People from comprehensives appear to be very motivated and have something extra which enables them to do well."
His paper, written with Professor Peter Sloane of the University of Aberdeen, and Dr Sarmisha Pal from Cardiff, stops short of advocating lower university entrance requirements for comprehensive school candidates, but suggests universities should examine their admissions policies.
The study compared students of the same sex, age, A-level grades and family backgrounds attending universities, which were grouped by size, teaching and research performance. When all these factors were taken into account, it found that comprehensive pupils outperformed independent school pupils. The type of school a pupil had attended was one of the strongest factors determining whether he or she achieved a first. In addition, former comprehensive school pupils were more likely to be awarded a better class of degree.
The research looks only at students from the old universities, not those at the former polytechnics. Earlier research carried out at Oxford University in the Eighties suggested state school pupils admitted to the university were more likely to get good degrees than their independent school counterparts.
At present, Oxford and Cambridge are campaigning hard to attract more comprehensive school pupils. Only about half the undergraduates at the two universities come from state schools. Cambridge has said that it would like to increase the figure to 65 per cent, the proportion of those who get three grade As at A-level who attend state schools. Though no university officially makes allowance for an applicant's background, some Oxbridge colleges say they bear it in mind when deciding whether to admit students.
The Cardiff study's main purpose was to examine the difference in academic achievement at degree level between the sexes. It found women performed better on average but were less likely to get a First than men. Mature students and those with no formal qualifications, as well as those at comprehensive schools, tended to get better degrees.Reuse content