Today’s Pisa results show that,  compared with 2015, Scottish attainment has gone up in reading, has dropped slightly in mathematics, and has dropped quite a lot in science. But even in reading, all this does is take Scotland back to where it was about a decade ago.

Scotland has essentially stagnated since 2006, after a sharp fall from the beginning of the century. The recovery since 2015 doesn’t fully compensate for the fall between 2012 and 2015. This recovery from 2012 to 2015 is the only positive story in the data. That’s why looking at the longer trend is important. It’s worth bearing in mind that Curriculum for Excellence started around 2010.

On the other two domains - maths and science - the picture is even worse than in 2015, which was widely seen at the time as a crisis. Moreover, the rise in reading attainment in 2018 has happened in the rest of the UK, too, where maths has improved and science has fallen less sharply than in Scotland.

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In reading, Scotland is better with low attainers than England, but worse with high attainers. In the other two domains, Scotland is consistently worse than England.

So highly able students are doing consistently better in England than in Scotland. Students of low ability are also doing better in maths and science in England than in Scotland. If low‐ability students are doing better in reading in Scotland than in England, that appears to be at the expense of Scottish high attainers in reading.

In each domain, the Organisation for Economic Cooperation and Development (OECD) defines these as people getting marks in approximately the top 10 per cent of attainment. That would correspond approximately to the top quarter of university graduates.

The proportions of Scottish students reaching this level of attainment are: 10.4 per cent for reading; 10.7 per cent for maths; and 7.2 per cent for science.

So, Scotland is merely average in this sense in reading and maths, and is below average in science. This is despite being above average in the mean attainment.

In each domain, England does better. Many other countries have higher proportions of top attainers. It is from this group that future national and global leaders will come.

The OECD uses an index of “economic and cultural resources”. The clearest and least misleading measure of inequality is the gap between attainment in the top and bottom quarters of this index. Unlike all the Scottish government measures of socio-economic circumstances, this records children’s actual home circumstances, not the circumstances of their neighbourhoods. Thus, this index is much more valid as a measure of actual inequality than anything the Scottish government uses in its other publications.

It’s important to look not only at the gap but also at the levels of attainment in different groups. It would be possible, of course, to have low inequality because everyone is mediocre.

The information is available this year only for reading, not maths and science. It shows that low‐status students do as well in England as in Scotland, while high‐status students do better in England.

It would thus be highly disingenuous to say only that inequality in Scotland is falling and is less than in England. Inequality also fell in England, mainly by raising the low‐status students while also raising high‐status students. Scotland raised low‐status students by less and depressed high‐status students. It would not be reasonable to describe this as better progress towards equality of outcome in Scotland than in England.

To conclude, in reading, Scotland has taken a decade of enormous upheaval in schools to get back to where it started. In maths and science, the decline continues. In England, the advance is steady in reading and maths, and there is a weaker decline in science than in Scotland.

Despite a decade of austerity, students facing difficult socio-economic circumstances do better in England than in Scotland. Scotland’s overall performance is best described as stagnating in mediocrity.

Lindsay Paterson is a professor of education policy at the University of Edinburgh