A LACK of reliable data means less is known about the performance of Scotland’s schools than at any time since the 1950s, a leading think-tank has said.

Reform Scotland said informed discussion is no longer possible because the Scottish Government has scrapped domestic surveys of pupil performance and withdrawn from international surveys.

The exception is the Programme for International Student Assessment (Pisa), which last week showed record low results in science and maths among Scottish school pupils.

Lindsay Paterson, professor of education policy at Edinburgh University, said Scottish education policy is now “based on speculation, ideological whim, and partisan rivalry”.

But Education Secretary and Deputy First Minister John Swinney insisted there is now “more performance data than ever before”.

Keir Bloomer, one of the architects of the Curriculum for Excellence teaching programme introduced to Scotland's schools in 2010, hit out at the lack of factual information to inform debate.

He said: “The Scottish Government has proclaimed education its highest priority. Other political parties share the view that it is vital to the future of the individual and to that of society and the economy. Yet there is legitimate concern about whether the system’s performance is satisfactory.

“A debate rages about how our schools, teachers and pupils are performing, with many statistics exchanged but few incontrovertible conclusions being reached.

“The continuing disagreements say something important and profoundly unsatisfactory about the information that is available.

“There ought to be a solid foundation of factual information that will allow constructive discussion to take place. Unfortunately, no such foundation exists. Pisa is the only example of international comparison available. Yet, even when the message was as damning as last week’s results, there is an official unwillingness to face facts.

“Has there been a narrowing of subject choice in S4? Has it been accompanied by a fall in standards? Is performance in Higher rising or falling? Is the proportion of young people leaving school without any qualifications reaching an alarming level?”

Mr Bloomer, who is the chair of Reform Scotland’s independent Commission on School Reform (CSR), added: “We know less now about the performance of Scotland’s schools than at any time since the 1950s."

A paper produced by the CSR insists “the data for an intelligent and constructive discussion simply does not exist”.

It said it is essential “that there should be good quality objective evidence of the standards being achieved and the difference that occurs when changes are made as, for example, through the introduction of Curriculum for Excellence”.

An important backward step, the CSR said, was the decision to abandon the Scottish Survey of Literacy and Numeracy (SSLN) after the 2016 survey.

Meanwhile, despite Scotland being closely involved in the development of international surveys of educational standards, it has pulled out of two of the three studies it previously took part in.

Mr Paterson said: “In practice, the evidence base for Scottish education has deteriorated drastically. Scottish education policy is now based on speculation, ideological whim, and partisan rivalry. No worthwhile policy making is possible in such a context.”

The CSR called on the Scottish Government to introduce a new sample survey and re-join international studies.

Mr Swinney said performance data includes "achievement levels for children in primaries one, four, seven and third year of secondary and comprehensive data on qualifications, achievements and awards in the senior phase".

He said: “We track young people’s destinations when they leave school and we publish a dashboard with performance information on primary, secondary and special schools across the country."