Value subtracted from inner cities
VALUE-ADDED measures are misrepresenting inner-city schools and their achievements, according to unpublished research.
As a result it appears that schools in deprived areas are failing to boost their pupils' performance, says the National Foundation for Educational Research.
However, value-added analysis is not yet sophisticated enough to do justice to urban schools with high levels of poverty and little parental support, says Dr Ian Schagen, NFER's head of statistics.
His verdict will disappoint ministers who are hoping that a simple "value added" measure - to be introduced next year - will be fairer to inner-city schools than the publication of raw examination results.
Dr Schagen's investigation of GCSE data from 93 schools showed that the schools which got the worst ratings through value-added analysis were usually urban or inner-city schools with high numbers of pupils on free meals or with special needs.
He found that even a complex "value-added" analysis - taking a school's catchment area, size and the percentage of pupils eligible for free meals into account - made little difference to its ranking.
The Government plans to publish national data based on a simple value-added model comparing pupils' results with their previous achievements.
But critics argue that more complex analysis is needed to take a school's socio-economic background into account.
Dr Schagen believes that, to date, no analysis has been devised that successfully accounts for all the factors associated with poor pupil performance.
He said it appeared that so far the methods used to take school context into account "do not make enough allowance for factors which clearly affect the way in which schools perform.
"Until we can do this reliably, even "value-added" measures of school effectiveness are likely to be misleading."
Dr Schagen's on-going analysis supports a recent NFER report, Value-added measurement of school effectiveness: an overview, which called for further research into pupil and school-level factors associated with performance.
Its author, Lesley Saunders, head of the NFER's school improvement research centre, said: "Value-added methods of evaluating school performance are certainly an improvement on raw results, which say a lot more about the intake than the effectiveness of a school."
But she warned that value-added measures could only ever be as good as the data on which they are based and that they dealt in correlations not causes.
Entitlement to free school meals, for example, is not a cause of below-average performance, although there is a correlation.