ADAM RAMSAY Students from state schools do better at university than students from private schools. Society is unequal. Schools are unequal. The only way that universities can be sure of getting the best students is to require lower exam results of those at difficult schools.

In 2002, academics at Warwick University compared the final grades of students at universities across the UK. They found that students from state schools were more likely to get good grades than their classmates who went to private school. This finding is not surprising.

Private schools are very good at getting their pupils the exam grades they need to get into top universities. The fact that they have got these grades does not mean that these students are bright enough to thrive once at university.

On the other hand, state schools in underprivileged areas are often less good at preparing their pupils for university entrance. For pupils at these schools to get the same grades as their colleagues at private schools often requires more raw talent, and more hard work.

By the time they get to their final exams at university, the difference in quality of school is less important than the difference in quality of student. This is especially true at Scottish universities, where the four-year degree gives students time to catch up - or fall behind.

Forty-one per cent of St Andrews students went to private school. The Scottish average is 14%. Somehow, something is going wrong. It is not because of snobbery. It is not because of an "old boys' network".

It is because, on the whole, a private-school pupil will do better in their exams than a state-school pupil with the same capability. Given the choice between these two, it is all too easy to pick the private-school pupil with slightly higher grades.

But this is the wrong thing to do if you want to pick those students who will, ultimately, do best at university. In selecting students, universities must look at the context in which grades were attained as much as they consider the grades themselves.

In The Herald's interview on Monday with Brian Lang, principal of St Andrews University, he said he thinks St Andrews has risen through the league tables in recent years because he has "not compromised on excellence".

Yet St Andrews expects all its applicants to get the same grades, no matter where they went to school. By taking into account the circumstances in which school grades have been attained, you are not lowering the bar. You are remembering that academic potential cannot be understood through exam grades alone. Private schools are exceptionally good at getting their pupils top exam results. The fact that pupils have been spoon-fed does not mean that they are brighter. It is because of a long-term failure to look at such contexts that those state-school pupils who do get into university ultimately do better than their classmates from private school - they have had to work harder to get there.

Exam grades are not the only problem. Proportionally more private-school pupils apply to top universities. St Andrews has some good programmes to widen access. As The Herald reports, it does good work in raising the aspirations of pupils in working-class areas of Fife. Also, it is unfair to blame Lang for the broader problems of an unequal society, and of an exam system which separates the middle class from the working class as much as it separates the very bright from the bright.

There are very bright pupils at private schools. They deserve to be at top universities. There are excellent state schools. But, on average, state-school pupils have to work harder - and be brighter - than their private-school counterparts in order to get the same grades. Universities must recognise this if they are going to have a fair applications process, and get the best students.

This is important. We live in a knowledge economy. Access to the best universities often means access to the best jobs. Our top universities are training the leaders of the future. Our top universities advance knowledge, and shape the world my generation will live in. There are huge numbers of applicants to universities such as Edinburgh and St Andrews. The vast majority will always be turned away. The evidence shows that we are turning away very bright state-school pupils in favour of bright, but less bright, private-school pupils. This means that our universities suffer, as they do not have the brightest students possible. It means that society suffers, as our universities don't make the progress they need to. It means that we perpetuate the elites of past generations.

Getting university admissions right is a massive challenge. It is not one we can afford to fail.

Adam Ramsay is president of Edinburgh University Students' Association.