Scottish Liberal Democrat leader Willie Rennie has today accused the SNP of rigging the Pisa educational survey to deflect poorer performance after an academic found the number of pupils withdrawn or deemed ineligible in Scotland is "much higher than in any other country".
Analysis by Professor John Jerrim published in TES shows that the proportion of Scottish students withdrawn or deemed ineligible from the 2018 Pisa test – which measures 15-year-old students' performance in maths, reading and science – doubled from 4.1 per cent in 2015 to 9.3 per cent in 2018. The average student withdrawal rate across all the countries that took part in Pisa 2018 was 1.7 per cent.
Many more tests were taken in S5 in 2018 than in previous years, meaning the survey will capture far fewer people who leave at the end of S4 and causing these pupils to be marked "ineligible". It also means more pupils are assessed in S5 when they have been in school for longer.
Professor John Jerrim stated that if non-participants had actually taken the Pisa test, Scotland’s scores "could change quite dramatically" and a plausible scenario is that Pisa 2018 results for reading would be 13 points lower.
The 2018 PISA results recorded Scotland's worst ever scores in maths and science, with England performing better in every measure.
Willie Rennie said:
"Scotland's rate of withdrawn students looks suspiciously like an attempt by the Scottish Government to rig the PISA results to distract from their disastrous handling of Scottish education.
"By shifting when many of these tests are taken pupils who leave at the end of S4 have been removed.
"For these international rankings to provide useful insights into the state of Scottish education, they must be rigorous. Selective sampling might make the picture look a little rosier in the short term but that will come at the expense of Scottish education in the long run.
"John Swinney deserved to lose his job over his handling of exams last year. There is chance for change at this election. Scottish Liberal Democrats will put recovery first for education."