A new report from Ofqual has shed new light on how centre-assessed grading produced by schools changed outcomes for pupils in 2020 after the dramatic U-turn in the way GCSE and A-level results were awarded.

The analysis, published today, looks in detail at the unmoderated centre-assessed grades that were used last summer after Ofqual ditched its attempt to use standardised grading.

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It finds that centre-assessed grades (CAGs) were half a grade higher on average than GCSE and A-level grades in previous years but adds that “they did not introduce any substantial bias or different patterns of grading”.

The paper also finds that “the strongest predictor by far of grade outcomes was a candidate’s prior attainment for both GCSE and A level” and that this relationship was slightly stronger in 2020 when compared with previous years.

Ofqual says that this may be because CAGs filtered out “unpredictable” variations in outcomes for pupils, for example, exam anxiety, last-minute revision or a particular combination of questions in an exam paper.

“Alternatively, it may represent teachers’ over-reliance on prior attainment as a source of data and not sufficiently taking into account individual candidate differences in performance,” it added.

Other key findings in the report include:

Slight drop in GCSE grades for students on free school meals

The research found that “students that were eligible for free school meals had a slight relative decrease in outcomes in 2020 with grades that were on average 0.06 grades lower than in 2019, suggesting a small negative effect on this group”.

The attainment gap between boys and girls decreased at A level

While boys had previously outperformed girls at A level, this gap was slightly reduced in 2020. This could either mean a genuine narrowing of the attainment gap, or a slight bias in favour of girls in centre-assessed grading, the report says.

Qualitative research from Ofqual found that teachers said boys are more likely to show a “last-minute push” before exams which was difficult to factor into CAGs in 2020.

Pupils attending schools with higher levels of deprivation achieved relatively higher grades compared with previous years, closing the attainment gap with more advantaged peers.

The report says this may also be because these schools had more “headroom” to travel up the grade range because they tended to have lower prior attainment.

Private schools fared better than others

The grades of private school students also increased slightly more in 2020 compared with other school types at both GCSE and A level.

“There was also some evidence that grammar schools’ outcomes increased more than those of mainstream secondaries at GCSE, particularly in the probability of candidates attaining C or above,” the paper says.

And for sixth-form colleges, A-level grades were relatively less generous in 2020 by 0.12 grades on average compared with 2019, whereas in previous years, “candidates at sixth-form centres usually outperformed secondaries by on average around 0.06 grades”.

Schools with missing prior performance and value-added data - essentially those entering a subject for the first time - also had relatively higher grades in 2020 than in previous years. In normal years, these schools tend to have lower than average outcomes whereas this was not the case in 2020.

‘Facilitating’ subjects were graded more generously at A level

Facilitating subjects - those seen as being commonly preferred by universities for access to academic degree courses - were graded slightly more generously, by 0.4 grades compared with 2019.

The greatest grade increase was seen for subjects in the “expressive” group, such as art and design, where grades were 0.48 grades more generous than in the previous year.

Summer babies did better

Another interesting finding from the research is that the overall effect of birth date was reduced in 2020.

“Fairly consistently in 2018 and 2019, younger students tended to have slightly lower grades by around 0.04-0.05 grades per quarter of the year, whereas in 2020 this effect was reduced to only around 0.02-0.03 grades,” the paper says.

Small cohorts achieved slightly higher grades

“There was also some indication that small cohorts received marginally higher CAGs than larger cohorts in 2020 compared with previous years, after accounting for subject and centre type differences,” the paper says.

“We suggest this may be because teachers of small cohorts had less consistent data to anchor their judgements, as outcomes for small groups are naturally more variable between years. This may have led to some additional generosity for these groups due to this increased uncertainty.”

The paper also says there is a small change in the effect of cohort size at A level. In previous years, both large and small cohorts attained 0.02 grades higher on average than medium-sized cohorts.

“Whereas in 2020 there seems to be a small cohort advantage, with small cohorts attaining grades on average 0.06 grades higher than previously compared to the medium group and large cohorts attaining grades 0.03 lower,” it says.

The effect of the region of the country on pupil outcomes was also weakened in 2020 at A level.

But overall, it notes that school or pupil level effects combined explained less than 1 per cent of variation in grades at A level, with most grade variation explained by prior attainment or “between candidate differences not explained by any of the variables included in the analysis, and additional unexplained variation in grades”, such as motivation, exam preparation or teaching quality.

“For the A-level models, prior attainment explained the largest proportion of variance of any of the fixed-effect variables included in the models for all years,” the paper says.

“In addition, in 2020 the variance explained by prior attainment was notably higher than in previous years by 6-7 per cent, suggesting that prior attainment is a stronger predictor of grade in 2020 compared with previous years.”

The average increase in grades was lower at GCSE

At GCSE, the average increase in grades was slightly lower than at A level, with a boost of 0.4 grades in 2020.

As with A levels, “small cohorts saw on average greater grade increases than larger cohorts”, and across school types, colleges had particularly large increases in mean grades.

“As for A level, there is evidence of a plateauing of the relationship with prior attainment for the highest prior attainment group,” the paper says - because candidates with lower attainment have further to travel.

EBacc subjects were not graded more generously

“There was no clear pattern of generosity related to whether a subject was included in the EBacc [English Baccalaureate] or not,” the paper says.

It also suggests that subjects with more coursework “were generally more generously awarded” than those with less coursework.

The smallest increases compared with 2019 were in subjects with no and a low percentage of coursework and the highest increases were in subjects with medium followed by high levels of coursework, “although subjects normally assessed via 100 per cent NEA [non-exam assessment] were again closer to the average”.

Expressive subjects, languages and humanities were generously graded whereas STEM subjects (science, technology, engineering and maths) were the least generously graded.

The relationship between prior attainment and outcomes ‘plateaued’ at the top grades

The research notes that because of an increase in the mean grade, at the top grades there was a “plateauing” of the relationship between prior attainment and outcomes at both GCSE and A level.

It said this was slightly more pronounced at GCSE.

“Effectively in 2020, candidates with the highest prior attainment received on average slightly smaller increases in grades compared with previous years as they were already attaining the highest grades possible,” it says.

Meanwhile, schools with lower previous performance or pupils with lower mean prior attainment saw the largest increases in grades. The paper says this is because these schools had “greater headroom” and therefore “further to travel” up the grade range.