Researchers at the Scottish Qualifications Authority have been looking closely at all aspects of the approaches it uses to revise exam results - derived grades, estimates and appeals.
Having heard the outcome of the review, the SQA board agreed last Thursday to get rid of the only part of the exam process which is not based on evidence of pupils' work.
Derived grades are based on teacher estimates of the grade they expect their pupils to attain. If they under-perform, they are automatically upgraded as long as enough other pupils at the school achieve their predicted marks.
This has run into the criticism that, because it is a statistical process, it does not scrutinise candidates' work. And, because it requires high numbers to make the process statistically reliable, it favours schools and subjects presenting large numbers of pupils - in effect, the charge has run, it disadvantages schools in deprived and rural areas.
The SQA has always resisted such claims, arguing that pupils who feel aggrieved can appeal against their marks. But its own research has now confirmed, in the case of schools in deprived areas, that the derived grades procedure "serves their interests less well than the appeals procedure".
In his letter to presenting centres, Tom Drake, the authority's interim chief executive, acknowledges that awards based on evidence, such as course assessments or appeals, "are more reliable and accurate measures of candidate performance than awards made on the basis of the derived grades procedure, which are determined using a statistical process".
The SQA board appeared to take its decision essentially on the grounds of equity, acknowledging that derived grades introduced bias into the system.
The research showed that some pupils' results did not deserve to be upgraded.
Mike Haggarty, spokesman for the SQA, suggested they had also been able to take the decision because of "the increased professionalism of teachers who have become much better at estimating their pupils' performance and, through working with us, have a better understanding of standards".
One result of this, he adds, is that the number of appeals has been falling since the "meltdown" years after the 2000 crisis - from a high of 85,066 in 2002 to 43,355 this year, although the SQA has also limited the number of appeals a school can make.
The SQA believes it can cope with any increase in appeals following the disappearance of derived grades. Its confidence stems partly from the relatively small numbers who have benefited from derived grades - last year 8.4 per cent of Standard grade courses were upgraded under the system but only 1.8 per cent of entries for National Qualifications.
One principal teacher at an independent school, who is also a principal assessor for the SQA and did not wish to be named, said he knew of schools and teachers who had abused derived grades to their advantage.
But he predicted "a huge impact on the SQA" from an increased number of appeals. His own department would have had 40 per cent more appeals last year.
He suggested that, as an alternative, the SQA could have looked at whether the level of "concordance" required for derived grades to kick in was appropriate; an under-performing candidate will be upgraded only where there is 60 per cent agreement between predicted performance and results for other pupils.
One prominent critic of derived grades, Elizabeth Doherty, headteacher of St Columba's High in Gourock, who wrote last year in The TESS that they were unjust and discriminatory, welcomed the decision to scrap them. "The system did not turn out to be as fair an opportunity for all people as it was hoped it would be," she said.
However, Mrs Doherty hoped the Scottish Qualification Authority would relax its current ruling that schools can make appeals for only 10 per cent of presentations.