A MAJOR review of the implementation of Scotland's troubled new curriculum is hamstrung by a lack of vital school information, experts have warned.

The Royal Society of Edinburgh said a forthcoming investigation into the Curriculum for Excellence (CfE) would find it impossible to draw "valid conclusions" about any impact of the reforms.

A report by the society's education committee said the problem had arisen because no proper baseline assessments had been done before the introduction of CfE, while the Scottish Government has also withdrawn from a number of international educational surveys which benchmark quality.

The warning comes after ministers announced in September last year that experts from the Organisation for Economic Co-operation and Development (OECD) would be called in to evaluate the controversial reforms of what is taught in schools.

The Paris-based, set up to improve the economic and social well-being of people around the world, is due to report in December 2015.

A report by the society's education committee states: "The absence of a systematic programme of independent evaluation of CfE has been a long-standing and key concern of the education committee.

"Without high quality evaluation, not only do we not know what is going well and what is not, but we have no way of developing a proper understanding or an ability to plan so that improvements can be made.

"It is our understanding that the OECD review will not undertake an in-depth evaluation of the impact of CfE. Rather, it will adopt a broader, forward-looking perspective on how the CfE reforms are being implemented, making recommendations it deems to be appropriate."

The committee said a proper evaluation of CfE would require "much preliminary investigation" as to the range of ways in which the curriculum is being introduced in different parts of the country.

It adds: "However, the RSE believes that it would be extremely challenging for anyone to undertake a thorough and rigorous evaluation of the CfE reforms, especially their impact on outcomes for learners.

"The absence of a systematic strategy has meant that independent evaluation has not been considered as a central feature of the CfE reforms from the outset.

"It is notable that no pilot studies were undertaken prior to the universal roll-out of CfE, and that no dedicated baseline data were collected that would enable any effect of CfE to be assessed.

"In order to establish an evidence base, independent monitoring and evaluation should have been explicit from the introduction of CfE. In the absence of such prior evidence, it is impossible to draw valid inferences about any effects of CfE."

The warning comes as the spotlight continues to focus on whether CfE has delivered significant improvement to education in Scotland despite the successful introduction of new exams this summer.

CfE was supposed to make subjects more relevant, free up teachers' time and develop more relevant skills among pupils, but it has been dogged by concerns over teacher workload and confusion over when pupils decide to study particular subjects.

The only independent academic study into the reforms, by Stirling University, found significant variation across schools and identified teacher concerns about growing workload, a lack of time for preparation and "vague" national guidelines.

More recently, research found the new curriculum was characterised by "confusion" over the underlying importance of subject knowledge

Researchers from Stirling University found a lack of coherence in the way official documents explained the importance of knowledge as part of the roll-out of CfE.

As a result, while the role of developing skills in pupils such as problem-solving and leadership is clear, inconsistencies in statements on knowledge were "undermining".

Mike Robinson, chief executive of the Royal Scottish Geographical Society, recently said crucial scientific elements of geography had been "stripped out" of new courses.

He also warned many councils were now using non-specialists to teach geography alongside other subjects such as history and modern studies.