Authors: Ben Smith, Andrew Boyle, Stephen Morris

EEF Research Paper Series, No. 004, February 2020

EEF response: National test results, such as GCSE grades, are an outcome measure for numerous EEF evaluations. However, any intervention aiming to improve grades must operate via improving students’ marks. This paper examines the impact an intervention could have in terms of improving students’ marks in their GCSE Science exams and implications for a trial’s MDES.

In a first step, the authors scrutinised GCSE papers to determine how many marks could plausibly be gained due to the intervention. Mark distributions were then simulated to assess what mark gain was likely in practice. Finally, implications for MDES and sample size calculations were examined.

This work has been conducted as part of the Deeper Thinking project and can inform MDES and sample size calculations of future EEF evaluations by considering the impact of marks.