School rankings based on the measure of contextual value added (CVA) – as used in the league tables due to be published tomorrow – are largely meaningless, according to new research from the Centre for Market and Public Organisation (CMPO) at the University of Bristol. The study by Dr Deborah Wilson and Anete Piebalga finds that almost half of English secondary schools are indistinguishable from the national average.

Parental choice among secondary schools in England is informed by annually published ‘achievement and attainment’ tables. The 2006 tables included the CVA measure for the first time. By explicitly accounting for the characteristics of a school's intake, CVA should provide a more accurate measure of the impact a school has on its pupils' progress, that is, on school effectiveness.

The Bristol study uses UK government administrative data to replicate CVA and other key performance measures in order to investigate the extent to which the current league tables provide the information necessary to support parental choice on the basis of school effectiveness.

The results show that while CVA does provide a more accurate measure of school performance or effectiveness, the school rankings it generates are largely meaningless.

Dr Wilson said: “Parents need to be able to distinguish between effective and non-effective schools. But the CVA shouldn't be on the league tables.

“What we have is a useful piece of information that is being misused. It is a useful measure for schools and policy-makers, but parents shouldn't be led to believe they can rank schools according to CVA.”

‘Accurate performance measure but meaningless ranking exercise? An analysis of the English school league tables’ by Deborah Wilson and Anete Piebalga is published as CMPO Working Paper No. 176(PDF 407Kb).