Durham University 'Academic Value Added' Research, 2016

Attending an independent school in England is associated with the equivalent of two additional years of schooling by the age of 16, new research reveals.

The 'academic value added' report by the Centre for Evaluation and Monitoring (CEM) at Durham University, is the first of its type. It looks at the differences in attainment between pupils who are educated in independent and state schools from junior or prep school through to GCSE, controlling for differences such as prior ability, socioeconomic status and gender.

In the research, commissioned by the Independent Schools Council (ISC), it is also revealed:

• Independent education is favourable academically at ages four, eight, ten and 16.
• Independent schooling accounts for a 0.64 of a GCSE grade increase.
• At GCSE independent schools have higher average scores in all subjects; Greatest differences are found in French, history and geography; Smallest increases are found in chemistry, physics and biology.
• If independent schools were measured on international PISA outcomes, they would outperform the best European nations and be level with Japan and South Korea.

Evidence has long suggested independent school pupils enjoy greater 'academic value added' and relatively higher returns for their education. But despite much interest in the subject and various other studies over many years around the world, few had given clear, robust and statistical evidence to determine the extent to which differences in academic achievement could be credited to attendance at independent schools alone, without factors such as prior ability and family background being considered.

The researchers employed a statistical procedure to control this bias, details of which are reported in the paper. With these factors taken into account, the researchers note "the evidence from this study suggests similar students achieve more in independent schools than in state school."