The proportion of A grades given to Scottish school pupils has increased by an average of 16.7 per cent since a new model has been brought in as a result of the pandemic.
Exams were cancelled this year as a result of the pandemic and the Scottish Government moved to a teacher-led model of grading.
Last year the use of an ill-fated algorithm led to protests from pupils and a vote of no confidence in then-education secretary John Swinney.
But figures released on Tuesday show a rapid increase in the number of pupils given the highest grades in the top three qualifications.
However, Professor Lindsay Paterson said the SQA had questions to answer around “grade inflation”, stating the significant rise in the number of A grades would raise eyebrows.
The professor of education policy at Edinburgh University said: “The most striking feature of these results is the massive rise in the proportion of candidates who were awarded an A.
"If the SQA claims that there has not been grade inflation, then how do they explain that students just two years ago, with mostly the same teachers as now, learnt so much less than students today?
"The explanation does not lie in teachers’ leniency, because they were only following SQA rules. It is the SQA that has cast such doubt on the credibility of Scottish qualifications.”
On average, the number of students given an A this year is 16.7 per cent higher than in 2018/19.
This year, 46.7 per cent of National 5 entries were graded the highest, compared to 35.1 per cent before the pandemic.
For Higher students, 47.6 per cent of entries were given A grades, up from just 28.3 per cent in 2018/19, while a similar increase was seen in Advanced Higher grading, with 51 per cent of entries grading the highest compared to 31.8 per cent two years ago.
Despite the changes, Scottish Qualifications Authority chief executive Fiona Robertson said she was confident that teachers had applied the national standard when grading, and cautioned against comparing this year’s figures with pre-pandemic levels.
Speaking after the results were released, she said: “We do see some variation in attainment and the composition of attainment every year and that’s to be expected between courses and over time.
“This year we are seeing more movement in attainment than we would see in a normal year when exams are held.”
She added: “I’m confident that teachers and lecturers have worked hard to apply the national standard this year, including support from SQA, and we’ve provided feedback on the application of the national standards.
“I absolutely acknowledge that A grade is up, but I hope that provides some helpful context.”
Education secretary Shirley-Anne Somerville said: “It’s very, very important that we have faith in the system and we have faith in our teachers.”
“The system was developed with teachers, with young people, with parents and with other academics to make sure it was fair and it was credible.”