The Vast new tables of statistics are supposed to shed light on schools' success in preparing pupils for the next steps of their lives. But a week after the government published the first "destination data" showing how many pupils individual schools have sent to leading universities, a heads' union has described it as "deeply flawed" and riddled with inaccuracies and omissions.
The Association of School and College Leaders (ASCL) said it was wrong to publish incomplete information, dating back three years, which does not recognise pupils who have secured full-time jobs. Employment data is not due to be included in the figures until next year.
The union is also angry that schools' success in getting pupils into university has not been fully credited. Students on gap years with deferred university entry - including those with highly prized places at Oxford and Cambridge - currently count as Neet (not in employment, education or training), the ASCL said.
Education secretary Michael Gove has long focused on the low numbers of free school meals children who win places at Oxford or Cambridge. But concerns have been raised that focusing on these two universities reinforces prejudice and could be damaging to schools in poorer areas.
Errors in the data have also been identified: one head complained that the statistics show that her school sent 11 pupils to the Russell Group league of top universities, when in fact it sent 24.
Brian Lightman, general secretary of the ASCL, said that the information could be helpful to schools, but should not have been made public. "It is a very important source of useful information for schools to have as part of their ongoing self-evaluation, but turning it into an accountable measure, especially when it is incomplete, can be misleading and damaging," he said.
It is more important to have data that shows whether schools are helping pupils to go on to endeavours that suit their needs, rather than narrow drivers such as Oxbridge entry, Mr Lightman added.
The union's deputy policy director, Duncan Baldwin, said he had been on the phone to a head who complained that the statistics were "drivel". "We asked for feedback from members and the gist is that it is deeply flawed," Mr Baldwin said. "It's so full of holes, it renders it meaningless."
One of the measures that the government has chosen - progression to Russell Group universities - has triggered concerns because it excludes many high-ranking institutions. Other universities, some of which place higher than Russell Group members in the Times Higher Education international rankings, such as St Andrews and Sussex, do not receive any special mention.
Eddie Playfair, principal of NewVIc sixth-form college in Newham, east London, said he recently doubled his Russell Group entry after Queen Mary, University of London, joined the group along with York, Exeter and Durham earlier this year.
But the "promotion" of the university will not show up in the figures, as they record 2008-09 school leavers. American or other foreign universities with a similar standing to Oxbridge do not appear in the data either.
The figures show stark regional variations in the numbers of pupils going on to higher education. In London, for example, 61 per cent of post-A-level pupils went on to university, compared with just 41 per cent in the South West. Mr Lightman suggested that this could be down to the proximity of pupils to a wide choice of local universities, rather than anything that schools can immediately influence.
David Day, principal of the Isle of Sheppey Academy in Kent, said that the tables reinforce what is already known about richer areas sending more pupils to high-performing universities. He added that it is equally important for schools to have "the ability to help young people secure employment with training, particularly when they come from a background of generations of unemployment".
But despite reservations from teachers, the data is here to stay. The government is calling for feedback on its latest statistics, which it describes as "experimental". Headteachers are also being invited to fill in an online survey about the data.
However, a briefing document makes it clear that the Department for Education is committed to holding schools to account over what happens to pupils when they leave. "[We are] continuing to test, develop and evaluate the data prior to moving towards publication in performance tables," it said.
61% - Greater London is the region that sends the highest proportion of post-A-level students to university.
41% - The South West sends the lowest proportion of post-A-level students to university.
28% - Reading is the local authority that sends the highest proportion to Russell Group universities.
7% - Reading also sends the highest proportion to Oxbridge.
16% - Colchester Royal Grammar is the school with the highest proportion of pupils going on to Oxbridge.
75% - Knowsley is the local authority with the lowest percentage of young people in sustained education.