Academy conversions create little benefit for weakest pupils, says think tank
Turning English schools into academies may have had no benefit for the least able students, according to research from a think tank.
A study of Labour's academies programme said there was "very little consistent evidence" of improvements for the weakest pupils.
The research features in a book about the lowest achieving fifth of students in England, dubbed the "tail".
The authors suggest there were "at best only small beneficial effects".
The book is published by Centreforum, a think tank with close links to the Liberal Democrats.
Introduced by Labour, academies have freedom to set staff pay and conditions, make changes to the curriculum and change the length of school terms and days.
The current government has expanded the programme, letting all maintained schools become academies.
The study by academics Stephen Machin and Olmo Silva examined the record of academies created under Labour up to the academic year 2008-09.
They write: "Irrespective of whether we rank pupils by the school or national ability distribution, the effects of academy conversion are insignificantly different from zero - and possibly negative for later conversions - in the bottom 10% and 20% of the ability distribution, suggesting no beneficial effects on tail students in academies."
A Labour spokesman said: "Labour's academies programme raised school standards and improved results in some of the toughest neighbourhoods and most challenging schools.
"However, we need to learn lessons on what the most effective education reforms are - which is why Labour plans to set up an independent Office for Educational Improvement to act as an impartial voice on evidence and data on education."
Schools' focus on the proportion of their students achieving five A*-C GCSEs can encourage them to neglect the least able pupils, says the report.
The Department for Education has proposed replacing the English five A*-C standard with an assessment of students' average performance over eight qualifications.
The Liberal Democrat education minister David Laws told BBC Radio 4's The World at One: "We're going to change the accountability system for secondary schools so that we will introduce a new measure that will give schools an incentive to improve the performance of every single young person.
"That will mean that instead of this tail of 20% of youngsters not being a priority for schools suddenly there will be a priority for schools for every single pupil."
The former Labour schools minister Lord Adonis, the current Conservative Education Secretary Michael Gove, and Mr Laws all support the book.
It suggests that US "Charter Schools", which like academies have greater autonomy than other schools, do better for disadvantaged pupils because many of the institutions have the specific aim of improving their attainment.
The chief inspector of schools, Michael Wilshaw, a former academy principal, told The World at One: "All the evidence shows where you've got good leadership which sues that freedom and autonomy and resources well and you've got a sponsor and a board of trustees that are really focused on achievement, it works.
"Where you don't have those two things then it doesn't work and they're not using those academy freedoms well."
The deputy general secretary of the National Union of Teachers, Kevin Courtney, said: "The findings confirm the union's well-grounded concerns that the obsessive focus on changing the structure of a school would divert attention and resources away from the core function of education which is to provide the best possible education for all students."