Claims that Britain ought to follow the German example by giving work-based training the same status as academic qualifications have been called into question by new research.
A report by Peter Robinson of the London School of Economics shows that people with degrees and the equivalent of A-levels in Germany and the United States earn far more than their counterparts with allegedly equal vocational qualifications.
The research casts doubt on earlier arguments that academic and vocational qualifications ought to be put on an equal footing, as suggested by Sir Ron Dearing and others. It also undermines the thinking underlying the government-backed National Targets for Education and Training.
In his latest report, Measure for Measure, Mr Robinson produces research showing that, after 20 years, graduates in Germany earn on average 25 per cent more than those with higher vocational qualifications, which are officially placed at the same level.
The same differentials are shown in earnings at all levels and reflect the findings of Mr Robinson's own research in the UK.
He says people with Scottish Highers, traditionally given the same status as A-levels, actually earn about the same as people with five O-levels.
Sir Ron Dearing's review of further education last year said that vocational training should be given "parity of esteem" with academic qualifications.
But Mr Robinson said: "Germany is often held up as an example of a country where vocational qualifications are much more highly regarded than in Britain.
"In practice German apprentices earn significantly less than those who have gained equivalent academic qualifications. It suggests that even in Germany there is no parity of esteem in the labour market between the vocational and academic routes."
In a report published last month, The Myth of Parity of Esteem, Mr Robinson produced evidence in a survey of 80,000 people that those with degrees and A-levels earned more than those with supposedly equivalent work-based training including national vocational qualifications.
His opponents argue that attempts to persuade employers to give vocational qualifications higher status can have some effect.
But Mr Robinson says the relative worth of qualifications is judged by the labour market which decides how much they should be rewarded in terms of earnings.
In his latest report he says: "Two qualifications can be said to be equivalent if they deliver similar labout market outcomes in terms of the jobs and the associated earnings to which they secure entry."
The National Education and Training Targets, launched in 1991, include the aim of 60 per cent of young people achieving two A-levels, an advanced general national vocational qualification or an NVQ level 3 by the year 2000.
Mr Robinson argues that one of the reasons that fewer than a third of medium and large employers have heard of the national targets is that they are not properly defined.
He also questions the rankings given to 32 qualifications by the National Advisory Council for Education and Training Targets.
Measure for Measure, a Critical Note on the National Targets for Education and Training and International Comparisons of Educational Attainment, Centre for Economic Performance, London School of Economics, free of charge