Official estimates of international students remaining in the UK are “potentially misleading” and should be treated with caution, according to the government’s statistics watchdog.
The investigation into the quality of long-term student migration figures – undertaken by the Office for Statistics Regulation – amounts to a rap on the knuckles for the Office for National Statistics, which has been advised to downgrade its estimates to “experimental” status.
In recent years ONS figures showing non-EU student inflow and outflow have suggested that around 90,000 former international students a year have remained in the UK.
The figures fuelled political demands to clamp down on student visas, an approach backed by Theresa May as home secretary despite complaints that it has harmed the UK’s lucrative education sector.
But the investigation cast doubt on the high level of students overstaying their visas.
“Former-student emigration could reasonably be expected to be lower than student immigration, due to the range of outcomes of former students, but it is unclear whether it occurs on the scale seen in the ONS estimates,” the report stated.
Ed Humpherson, the OSR’s director general, said the ONS’s migration statistics quarterly report (MSQR) – which contains estimates of migration to and from the UK – should carry more prominent health warnings on its limitations.
“I am concerned that the former-student emigration estimate does not bear the weight that is put on it in public debate,” Humpherson said.
“This estimate … creates doubts by not providing a complete and coherent picture of former-student emigration, as these figures alone do not provide information on all the different outcomes for international students.”
The report was welcomed by the Russell Group of universities, which has lobbied for international students to be removed from the UK’s migration statistics.
“International students make an enormous contribution to the UK and we need an immigration system that lets universities recruit the brightest and best to come and study here,” said Sarah Stevens, the Russell Group’s head of policy.
“If we are asking policy-makers to take decisions based on dubious figures it is hard to see how we can end up with a system of student immigration that delivers for the UK.
“The introduction of exit checks could help ensure that we are getting more accurate numbers, but this suggests that we still have a long way to go.”
The investigation found that the MSQR’s student migration balance was misleading because it compared data from different sources.
“This ‘balance of flows’ figure compares two different student migrant populations: those entering to the UK for formal study and those leaving the UK for formal study.
“Although the figure is a component of overall net migration, it is not a measure of student net migration; it does not reflect the outflow of students who originally entered the UK to study,” the investigation found.
The report concludes that until the ONS “has a more complete and coherent picture” of former student migration, the statistics should be labelled as experimental.
“With the benefit of hindsight, it would have been more appropriate to publish these statistics as experimental statistics when they were first introduced. This would have signalled clearly that the estimate, and any student net migration estimate derived from it, should be interpreted with caution.”
A new study by the Department for Education also published on Thursday found that UK education “exports” raised £18.8bn a year in 2014, a 30% increase compared with 2010.
Two-thirds of the earnings came in the form of tuition, expenses and research fees paid to British universities. Fees for independent schools accounted for £800m a year, while language schools accounted for £1.8bn.
Living expenses paid by non-EU and EU overseas students at British universities totaled more than £6bn a year.