The former chairman of England's exam regulator blamed "humans, not machines" for last year's A-Levels debacle.
Roger Taylor said Ofqual wanted to scrap A-Levels and offer “non-qualification” leaving certificates in their place.
The proposal was rejected by the UK government, which insisted pupils' grades should be calculated using an algorithm.
Acceptance of this decision gave way to uproar, when the machine-predicted grades led to many pupils missing out on their university of choice.
In the face of protests and pressure from the regulator, the Department of Education backed down and turned to teacher assessment to award grades.
This decision solved some of the problems but it was not without its flaws.
A recent study by the University College of London and the London School of Economics found that students whose parents had university degrees were 15 per cent more likely to get better grades through teacher assessment than through the Ofqual algorithm, even after accounting for social background and previous exam results.
Mr Taylor called the decision to use an algorithm a “colossal error of judgment” but he said the problem was not with the technology but in its application.
“The mistakes were made by humans, not machines,” Mr Taylor said, describing the decision to allocate university places on the basis of an estimate as “hopelessly naive”.
Universities should instead have made more places available for the following academic year to mitigate wrongful exclusions, he said.
“This option was, to my knowledge, never seriously considered. But by a painful, chaotic and unplanned route, it is where [we] ended up.”
Mr Taylor questioned the fairness of exams in normal times “when pupils also experience very different levels of educational support, differences that are reflected in the exam results they achieve.”
He was backed by Charlotte Alldritt, director of the Centre for Progressive Policy that commissioned the research.
“The pandemic has shown that examination results can and should only ever be part of a wider set of information available to young people, employers, education providers and policymakers,” she said.
