"Universities are important, but their importance is hugely increased if graduates stay in the area," argues Tim Leunig, reader in economic history at the London School of Economics, .
Dr Leunig makes the point in an analysis linking the strength of an economy to the number of graduates remaining in the region after completing their studies.
He cites a paper by academics at Cardiff and Swansea universities, titled "", noting that while Wales attracted 26,000 students from the rest of the UK in 2009-10 - compared with 16,000 Welsh students who chose to study outside the country - only 62 per cent of those graduating in Wales and in employment six months later remained there.
This compares unfavourably with Scotland, where the figure is 84 per cent, Northern Ireland (93 per cent) and England (94 per cent).
Furthermore, Dr Leunig points out that although only 58 per cent of students graduating from universities in Wales are Welsh, the overwhelming majority of graduates who find work and stay in Wales are natives of the principality (82 per cent).
"Wales is thus in the perhaps unlikely position of being a net gainer of students and a net loser of graduates, disproportionately losing outsiders who arrive to study and failing to attract back those who left to study elsewhere," he writes.
This, he says, paints a "fairly bleak picture" for Wales, since the "brain drain" results in a regional economy that is significantly less skilled than it would otherwise be.
Dr Leunig compares statistics for the proportion of the population aged under 45 with a degree in different parts of the UK.
It is about 18 per cent in Wales, he says, a similar level to most regions in England, but much lower than in London and the South East, where the figure is 26 per cent.
But he says that London and the South East are the outliers rather than Wales.
"That is both good and bad for Wales. It is good in that it suggests no particular failing on the part of Wales. But it is bad in that nowhere outside Wales has found a way to resist the pull of the South East for the brightest and the best," Dr Leunig writes.
"For these people the streets of London are perceived, at least, to be paved with gold, and they move accordingly."
The result, he contends, is that creating large numbers of graduates in an area should not be seen as a straightforward route to prosperity.
"Wales has more university places than its population would imply, but that does not lead Wales to be a wealthy place," he concludes.
"Universities are important, but their importance is hugely increased if graduates stay in the area. It is easy for the state to build universities, but not easy for it to ensure that students remain in the area after graduation."
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