Ministers have been accused of fixing figures to support their case for a voucher scheme for 16 to 19-year-olds.

Further education leaders challenged a Department for Education and Employment study suggesting the public pays the same amount for students irrespective of whether they are in schools or colleges.

They believed the DFEE formula used to prove an average school sixth form was as cost-effective as an average college was flawed.

They suspect that under pressure from critics the DFEE has now amended its formula to make the disputed findings look more convincing.

The Association for Colleges, which has joined the Colleges’ Employers’ Forum in questioning the DFEE study, privately believes ministers plan to use the findings to pave the way for a voucher scheme for 16 to 19 education and training.

A voucher scheme could only work if the costs of educating the age group in schools and colleges were reasonably equal. The DFEE analysis suggests funding for a student taking three A-levels is virtually identical in schools and FE colleges, and slightly higher in sixth-form colleges. These findings challenge the widely-held view that colleges are more cost-effective than schools.

In a detailed response to the study, the AFC and CEF say the comparisons are “seriously flawed” and lead to “simplistic and premature” conclusions.

DFEE statisticians weighed up the costs of individual qualifications in schools to compare them directly with colleges. It is this formula which the Association claims has been altered by the department. But the association claims although the formula changed, the DFEE still got the same answer for the average cost of a student taking three A-levels in a sixth form.

John Brennan, AFC policy director, said: “The original calculations bore no relation to the conclusions over school costs. Either they are now trying to steer the formula back, having been rumbled by trying to manipulate the figures, or this new formula can’t be trusted.”

AFC chief executive Ruth Gee said: “This demonstrates there is an awful lot more thinking to be done before we start making public comparisons which don’t stand up to scrutiny.”

The AFCCEF submission to the DFEE also questions the methodology behind cost comparisons between programmes funded by training and enterprise councils and by colleges, which it claims makes TECs look more cost-efficient than they are.

The document also calls for a clearer explanation from ministers of the policy agenda behind the costs study.

The AFC and CEF plan to join other further education associations, including the Sixth Form Colleges’ Association, to lobby the Government over colleges’ funding needs. They will campaign for greater investment in FE, claiming the settlement announced in last November’s budget will cut funding per student by a fifth by 1999.

A DFEE spokesman denied the formula for calculating sixth-form funding had been revised, saying college leaders had merely been given “more information” on the way the figures were reached. Associations would have a chance to raise their concerns during consultations on the study, he said.