Value-added league tables are worse than pointless and should be scrapped because they are unfair to schools in deprived areas, a leading academic has told The TES.
Official attempts to rank schools by their impact on pupils' performance are no fairer than raw league tables, according to a study by Stephen Gorard, York university professor of education.
He said the difference between value-added and raw league tables is like the difference between Celsius and Fahrenheit: "They are different scales but they both measure the same thing."
Professor Gorard called on the Government to stop publishing all league tables until it has found a fair way to compare schools. "Value-added tables are worse than pointless because their apparent precision may have misled analysts, observers and commentators," he said. "The size of this problem, once accepted for policy-making, for the local reputations of schools and for studies of school effectiveness would be difficult to over-emphasise," he added.
Professor Gorard's study of 124 mainstream secondary schools in Yorkshire found that schools' value-added score could be predicted by looking at their raw scores.
Value-added tables are used to identify schools that the Government believes are not doing well enough given their intake.
The Department for Education and Skills has now asked him to repeat the analysis using data for every secondary in the country and early results support his previous findings.
Professor Gorard said his study showed the limited effect schools have on pupil performance when compared to outside factors such as poverty.
His findings follow claims from Professor David Hopkins, a former government adviser, last month that 600 secondaries or one in nine are underperforming.
Professor Hopkins has now told The TES that the figure, a personal calculation based on value-added scores, may be an overestimate and could be 400.
But he said: "It may be that my number is slightly on the high side, but even if it is 400, we need improvement."
The Government has promised to crack down on coasting schools which it believes are letting down pupils in affluent areas by achieving lower results than they should do given their intake.
But controversy surrounds methods used to identify such schools which often have raw exam scores above the national average.
Office for Standards in Education inspectors have so far identified 13 secondaries and 47 primaries that are underachieving but not in the special measures or serious weaknesses categories.
In addition, there are 144 secondaries and 375 primaries which have serious weaknesses or are subject to special measures.
David Bell, England's chief inspector, has said that up to 1,000 schools do not improve fast enough between inspections. Both he and Professor Hopkins include coasting and failing schools in their totals.
One school which has beennamed by the Office for Standards in Education as underachieving is Our Lady's Roman Catholic in Oldham.
Roger Whitaker, headteacher, said the school had been singled out after last year's disappointing GCSE results when a number of pupils narrowly failed to gain the crucial five or more A*-C grades. He said: "Nearly 40 children got four A*-Cs out of a year group of 200.
"Children were doing too many subjects. An average child was doing 12-13 GCSEs.
"I would have felt miffed if we had gone into special measures or serious weaknesses.
"It is a peculiar situation ... But I have no problem with the inspectors'
judgements. If they had said everything is fine we could have easily taken our foot off the pedal."