Teachers are to be given better training in estimating their pupils' work and preparing evidence to back up exam appeals.
The move by the Scottish Qualifications Authority follows its findings that many teachers are poor at estimating pupils' exam performance and provide inadequate evidence for appeals.
The findings emerged as part of the SQA's investigation into its procedures for estimates, derived grades and appeals for national qualifications.
Last week, the exams authority announced it was withdrawing the derived grades element with immediate effect because, through its reliance on statistical processes rather than evidence, it had proved less reliable than appeals based on coursework and prelims. It was also found to have an inbuilt bias in favour of large schools and large subjects.
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.
Next month, the SQA is to publish revised guidance on evidence requirements for exam appeals. It is also planning further developments for its "understanding standards" programme.
The review said: "Half of the evidence submitted for appeals is rejected because it fails to meet several criteria. Incompleteness and unreliability of appeals evidence are the main reasons for lack of success, and often occur together.
"There is clear evidence that current arrangements are not functioning well, and there is work to be done to ensure that SQA's procedures are as effective as possible and to support teachers and lecturers in achieving the desired quality of estimates."
The advantage of enhancing teachers' ability in this area would be, says the report, a better understanding of standards, not only for use in exam preparation but also for teaching. The disadvantage is that to achieve the necessary impact would require a large-scale, long-term commitment from the SQA, local authorities and presenting centres, with significant resource implications.
The report says there are "compelling" reasons to address estimates, as they will continue to be used in a range of SQA procedures.
Developments such as Assessment is for Learning and A Curriculum for Excellence also rely heavily on teachers' judgment and will place more emphasis on school-based assessment.
Professor David Raffe, director of research at Edinburgh University's school of education, believes that part of the impetus for the Scottish Qualifications Authority's decision is the desire to support reforms such as A Curriculum for Excellence. Speaking in a personal capacity, he said:
"The most important implications are for the review of national qualifications that is currently under way. Everyone agrees that assessment and certification should support learning and the curriculum, not the other way round. "
Brian Cooklin, convener of the education committee of the Headteachers'
Association of Scotland, said his association had advised the SQA that it would have to loosen its appeals procedures if it withdrew derived grades.
Relying on evidence-based appeals would increase the workload for schools and staff would have to be released to deal with appeals, he said.
He agreed with David Eaglesham, general secretary of the Scottish Secondary Teachers' Association, that some schools came under pressure from pupils and parents to put in appeals, with some parents threatening legal action.