Growth in graduate numbers alone will not help countries improve their economies, the Organisation for Economic Co-operation and Development has warned. Universities must diversify the supply of graduates and keep the right balance in the number of academic courses and occupation- oriented courses, said Andreas Schleicher, the head of education indicators and analysis at the OECD. Mr Schleicher was speaking to a global audience on Tuesday in an online debate joined by experts and education journalists from across the world to follow up on the issue raised by the publication of the OECD's Education at a Glance report 2007. Although in many rich countries more than 50 per cent of secondary school graduates - and in some nations more than 75 per cent - were now going to university, expanding the proportion was not the only requirement to aid the development of knowledge economies. 'The challenge for higher education will be not to simply produce more academic graduates of the same kind, but to diversify the supply and to retain an adequate balance between academically oriented qualifications and ones that are more closely tied to occupational orientations,' Mr Schleicher said. Skills demands had risen across the board, to the point where education for jobs previously provided for through apprenticeships now required higher levels of qualification, he said. 'Take the job of a car mechanic. In 1930 all the coded information for a General Motors car would be captured in 230 pages. Now a single car involves some 15,000 pages of coded knowledge which workers will need to be able to access, manage, integrate and evaluate.' The topic was 'Education: Learn More, Earn More?' Questions were asked from experts as far apart as Chile and China, as well as OECD countries such as Britain, France and Spain. Sofia Otero Cavada, from Chile, asked if it was not just a question of countries keeping a balance between skills training and academic qualifications but between career subjects offered, which might for instance lead to too high a concentration on producing psychologists, journalists or lawyers. 'That is an important problem in many countries where the expansion of higher education has merely meant that universities produce more of the same graduates,' Mr Schleicher said. 'The challenge for modern universities is to diversify the provision to match a widening range of outcomes and participants.' He had no truck, however, with the common assumption, raised by a questioner from France, that expanding university places benefited the few and was a waste of resources for many, since this had been discounted by employment indicators. 'In many countries the belief is widely held that this is all a zero-sum game and as the proportion of university graduates increases, graduates will end up doing the kind of jobs that formerly were done by high school leavers,' he said. The 2007 Education at a Glance research was the first time the OECD had been able to compile quantitative evidence discounting this. Neither was there evidence that expansion created a dearth of lesser-qualified people needed to do lower skilled jobs. 'The employment and earnings prospects of individuals with lower skills have in many countries deteriorated, in some seriously. Continued automisation and outsourcing are likely to increase these pressures further. So we have no indicators of a shortage of low-skilled workers,' Mr Schleicher said. There was a warning note about graduate expansion, however, in an answer to Ana Yerro, of the Institucion Futuro, who asked why Spanish workers with a university degree only earned 150 per cent more than a worker without a degree, compared with much higher pay differentials for graduates and non-graduates in countries such as Hungary and the United States. Mr Schleicher said the earnings advantages of university qualification could be undermined by a number of factors, including the demand for qualifications, tax structures and the perceived quality of university education on offer. 'It is noteworthy in this context that, different from the general pattern across the OECD countries, Spain is one of the countries in which the earnings advantage of tertiary graduation has declined over the last decade. 'This has often been interpreted in the sense that the massive expansion of tertiary education in Spain has led to some deterioration in the quality of outcomes.' The OECD had no comparative data to examine this, however. Similarly there was no evidence that the best way governments could improve their education system was to plough money into it. Changing expectations Learn-to-earn skill demands have risen affecting how people are educated Percentage of students going to university in most rich countries: 50%