THE gap in problem-solving skills between rich and poor pupils in Scotland is equivalent to more than two years of education, according to a major international education survey.

The Programme for International Student Assessment (Pisa) carried out through the Organisation for Economic Co-Operation and Development (OECD) compares the performance of more than 35 countries worldwide.

The study, carried out in March 2015, analysed the collaborative problem-solving skills of 3123 15-year-olds at 109 secondary schools across Scotland.

Researchers said pupils from the most affluent backgrounds and the most disadvantaged pupils in Scotland differed by 74 points, adding "that would imply a difference of nearly two and half years' education".

However, the study found that despite a "clear link between background and performance" pupils in Scotland were "more likely to break away from the pattern of background affecting performance", scoring more than two percentage points under the OECD average.

Pupils in Scotland lag behind their English peers but are ahead of more than a dozen countries including Wales, the study found.

Scotland had a mean score of 513, above the OECD average of 500, but was outperformed by nine OECD countries – Australia, Canada, England, Estonia, Finland, Germany, Japan, Korea and New Zealand.

Northern Ireland, Denmark, Sweden, Austria, the Netherlands and the US all had similar scores to Scotland, while 19 OECD countries trailed behind it, including Wales, France, Spain, Norway, Israel and Iceland.

Researchers found the number of low achievers in Scotland were lower than the OECD average at 23.8 per cent compared to 28.1 per cent There were 9.8 per cent high achievers, above the OECD average of 7.9 per cent Scottish Conservative education spokeswoman Liz Smith said: "While there are a few encouraging signs, this Pisa report still points to a very significant attainment gap in Scotland and one which is more extensive than the gap in other competitor nations.

"Similarly, Scotland still trails behind England when it comes to the percentage share of high achievers.

"Like literacy and numeracy, problem-solving is an essential skill for all pupils, but these statistics suggests that the SNP is making no progress when it comes to narrowing the stubborn gap."

Deputy First Minister John Swinney said: "Curriculum For Excellence has always been about providing Scotland's young people with a comprehensive, rounded education that prepares them to thrive in today's world.

"The Collaborative Problem Solving PISA results show that the Scottish education system is performing well in this regard – and above the OECD average.

"Curriculum for Excellence has been OECD endorsed and I am confident that it is the right approach for Scotland.

"But we know where improvements are necessary and we are currently undertaking the biggest and boldest set of reforms to Scottish education in recent times.

"These will no doubt improve Scottish education and maximise the opportunities for all of our learners, creating an empowered school and teacher-led system, centred around the young person.

"The results today show us that our 15-year-olds have key strengths in the skills that are necessary for contributing to today's society."