A major investigation into the scale of off-rolling has found that one in every 10 pupils in Year 11 have had an unexplained move out of their secondary school.
The Education Policy Institute revealed that the number of these "unexplained exits" were higher in schools run by large multi academy trusts (MATs) than other schools and more likely to affect vulnerable pupils.
The report published today also found that there are some MATs, and maintained schools in particular local authority areas, with much higher rates of pupils leaving through unexplained exits than the average.
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The research looked at the cohort due to take GCSEs in 2017 and found around 69,000 unexplained pupil exits involving 61,000 pupils during the five years of their secondary education.
The EPI said today that their figures provided the most refined estimate to date of the potential size of so-called “off-rolling” in the school system – where pupils are taken from a school’s roll to boost results and school standings.
However, the EPI said it had used the term "unexplained exits" because the statistics cannot show whether each move was done in the school's interest or that of the pupils so cannot definitively be classed as off-rolling.
The figures for unexplained exits also include managed moves between schools which the EPI estimates account for 12.8 per cent of the total.
The EPI warned there were around 24,000 children who left school to an unknown destination who did not return to a state-funded school by the spring term of Year 11.
David Laws, the EPI’s executive chairman said: “These figures are disturbing and show that one in 10 pupils leave their school during secondary education for reasons that may not be in their interests.
“Almost half of these children fail to return to mainstream schools and it is concerning that the government has so little information on where many of them end up.
“Vulnerable children, including those in care and in poverty, are particularly at risk of having their education disrupted in this way – adding further disadvantage to the barriers they already face.”
He also called on the Department for Education and Ofsted to look into the local authorities and MATs with the highest numbers of unexplained exits.
Yesterday Tes revealed that a MAT has been accused of off-rolling after a document showed it had considered whether it could boost its league table scores by taking low-achieving students off school rolls.
Among the key findings of the EPI report is that there are over a dozen school groups where a pupil is at least twice as likely to experience an unexplained exit than the average, with those in the highest school group six times as likely.
The report’s author Jo Hutchinson, director of social mobility and vulnerable learners at the EPI said: “This research shows that there are thousands of pupils in England routinely removed from schools with no apparent explanation.
"While certain groups of schools display very high rates of pupil exits, it is also clear that this phenomenon pervades the entire school system, and requires intervention at a national level.
“The overwhelming majority of exits from school rolls are experienced by more vulnerable pupils, such as those with special educational needs and disabilities.
"The government should reduce perverse incentives for schools and do more to promote inclusion – only then will it help to prevent those with more complex needs from being moved around the system."
The report published today follows research the EPI produced in April which estimated that there had been 55,000 “unexplained” pupil moves in English secondary schools, raising concerns that many of them could have been “off-rolled” in a bid to boost exam results.