The Tomlinson inquiry into the future of 14 to 19 education did not have time to consider all available research evidence, says a member of its working group.
The 18-month inquiry called on a wide range of educationists and academics, but had too little time to get through its work, said Ken Spours of the Institute of Education, University of London.
"Its views about things were not dogmatic - they were grounded in a lot of experience and research," he said. "But I would not say the working group had utilised all or even a great deal of the available research.
"No one on the committee was anti-research. I just think if you're working over 18 months and you're working in very constrained phases, there's a limit to what you can do and a limit to how much you can draw upon."
Sir Mike Tomlinson's report, published last October, recommended a four-level diploma to absorb all vocational and academic courses over the next 10 years.
But despite the education world's firm support for the radical proposals, the Government is expected to compromise by leaving GCSEs and A-levels intact in its 14-19 white paper next week.
In an interview for a 16-page TES supplement this week on research in the learning and skills sector, Dr Spours says the review gave academics a golden opportunity to influence policy, as the Government called in a wide range of experts to help bale it out of the 2002 A-level crisis.
But the panel was hampered by time constraints, and available research was condensed by a Government appointee, he said. "So, for instance, we got a lot of research on vocational education international comparisons. We got very little information on learner identity.
"Even among relatively open people, a process of filtering does take place because the committee doesn't have enough time to consider all research."
Another member of the group, David Raffe, professor of sociology at the University of Edinburgh, said that, as work on the report progressed, there was a tendency to look for "bits of research that will fill in the gaps rather than question too many of the assumptions you've been working on".