Centres with a change in the number of students between years, and a change in their ability, are more likely to experience variability in GCSE outcomes. This is one of the findings from a recent study by Ofqual as it continues its research into the year-on-year variability of GCSE results at centre level.

Other findings from the study include:

• Whether a centre is stable or variable in one year is a predictor of stability or variability in the following year.
• Centres who experience positive volatility in one year are likely to experience negative volatility in the next.
• A significant amount of variability is not predictable – there are some features within centres that are difficult to capture such as changes in timetabling or to staff.
• Measures of socio-economic status have little or no bearing on year-on-year centre variability.
• The comparable outcomes approach to awarding examinations does not have a systematic negative impact on centres with higher proportions of low socio-economic status candidates.

Cambridge Assessment has also carried out research into this area which agrees that year-on-year variability is due to well-known predictive influences and because of differences in the profile of student ability.