Year-by-year fluctuations in exam results 'should be seen as normal'

Schools, assessors and policymakers should be more accepting of the fact that year-to-year variations in exam attainment levels among pupils should be seen as normal and predictable.

This is according to a new report from Cambridge Assessment, which has offered evidence that a certain degree of volatility in schools' GCSE results is quantifiable and inevitable, due to changes in the overall ability level of the student body in any given year, as well as simple chance.

For this research, GCSE performance data from between 2011 and 2015 was taken from the Department for Education's National Pupil Database, with statistical models used to estimate how much of the national variation in results could be explained by differences between schools, differences between years at the same schools, and differences between pupils within each cohort.

Once students' typical academic performance was added into their models, the size of the predicted year-to-year fluctuations was very nearly as large as those seen in practice, showing that the majority of volatility can be explained by normal variation in students' ability levels.

The researchers say these trends occur even if teaching practices remain the same, and is an unavoidable consequence of the fact that a different set of individuals take the exams each year. Accepting this can help schools to better understand the full range of performance outcomes that may occur.

They concluded: "Because there is chance involved, and because schools and their students change over time, it is natural that schools would see different results from one year to the next.

"The most important thing is that as a teacher, you don't know what mix of abilities you'll get in a particular class each year. Recognising this ensures we have realistic expectations of our education and assessment system."