DfE Advice on comparability over time:
‘Children sitting key stage 2 tests in 2016 were the first to be taught and assessed under the new national curriculum. The expected standard has been raised and the accountability framework for schools has also changed. These changes mean that the expected standard this year is higher and not comparable with the expected standard used in previous year’s statistics. It would therefore be incorrect and misleading to make direct comparisons showing changes over time. For example, it would be wrong to say that ‘the percentage of pupils nationally achieving the expected standard in reading, writing and mathematics fell from 80% in 2015 to 53% in 2016’.