In a normal year the opening of the window for checking school performance data and the release of updated national key stage 2 results is accompanied by the publication of the primary accountability guidance. Evidently this is not a normal year. Schools downloaded their progress data from the checking portal on 7th September; the guidance followed four days later and much of the methodology outlined in the annexes has not been updated since 2023.
This important document helps anyone working with school performance data to understand how the various measures are calculated. It explains which pupils are included in these measures, how pupils working below the standard of the test are handled, the impact of absence from tests and missing test scripts, and what happens if a pupil is out of year group. Perhaps most importantly this year – which sees the first progress measures since 2023 – the document goes deep into the mechanics of how KS1-2 progress is calculated. Trying to make sense of progress data without up-to-date guidance is like trying to navigate mountains without a map.
Since schools have accessed their progress data, issues have emerged. One, relating to the setting of prior attainment bands, is now well known and has been covered in the TES. The DfE have now identified that the threshold for the classification of high prior attainers (HAPs) was set too low – the KS1 average point score (APS) was set at >=8 rather than >8. This has resulted in a large group of middle prior attainers – including those that met expected standards in all subjects at KS1 – being incorrectly placed into the higher band. One school that contacted me stated that two thirds of the 2025/26 year 6 cohort are categorised as high prior attainers; in previous years it was no more than a third.
The DfE state that this will be ‘rectified in revised data and will show correctly in school level data published in December’ (i.e. when the performance tables are published). But provisional ASP and IDSR reports are due to be released before that, and this will likely cause headaches for schools. These reports are shared with governors, SIPs, consultants, LA advisors and inspectors who may ask awkward questions such as “why haven’t more of the high prior attaining pupils achieved greater depth at KS2?” Teachers will then have to explain the error and present a recalculation to counter it.
The DfE explains that the error ‘does not impact pupil and school level progress scores, it only impacts the low, middle and high prior attainment breakdowns for your school’. This has caused confusion because one might assume that if pupils are incorrectly categorised as HAP then their KS2 scores would be compared to the benchmarks that are too high and the resulting progress scores would be negatively inflated. It is important to note that these broad prior attainment bands are used solely for reporting purposes in the IDSR, ASP, and performance tables; they do not form the basis of progress measures, which involves sifting pupils into 20 prior attainment groups.
Pupils being incorrectly classified as high prior attaining is frustrating – and could result in some difficult conversations – but it has no bearing on the progress calculation. The incorrectly classified pupils – specifically those with a KS1 APS of 8 (EXS in all subjects at KS1) – will also be placed into a narrow prior attainment group (PAG) containing pupils with the same KS1 APS. Their KS2 scaled scores will then be compared against the average KS2 scaled score of pupils nationally with the same KS1 APS. Essentially, performance data has rough and fine filters: the rough filter (low/middle/high) is a broad classification for reports; the fine filter (20 PAGs) is used for progress calculations.
An analogy might be describing runners as fast, medium-paced or slow, for the sake of convenience, but for accurate measurement, we compare on the basis of age and gender. The mistake described above is like classifying all 54 year old men (like me!) as ‘fast’ but still correctly comparing their individual race times to the average time of a 50-55 year old man. ‘Fast’ is the broad prior attainment band; ’50-55 year old male’ is one of 20 prior attainment groups.
On the subject of prior attainment groups, below is a comparison of the 2023 and 2026 benchmarks. Note that 2023 and 2026 PAGs do not perfectly align due to changes in the APS ranges (see columns 2 and 3), but they are broadly comparable.
What is notable, are the big increases in some of the benchmarks when compared with 2023. An increase was expected – the 2026 year 6 cohort has had a very different experience to the 2023 cohort in terms of disruption to their education and when assessments were made pre- and post-Covid* – but increases of 3 or more points are eye-opening, and the 6 point increase in the reading estimate for PAG 17 is staggering. Meanwhile, there has been no change in the benchmarks for the highest prior attainment group.
We have to assume that the data is correct and attainment really has improved considerably for some of these groups. But there is also the possibility that there are errors in the calculations and issues with progress measures go beyond the misclassification of middle prior attaining pupils.
We will have to wait until December to find out. In the meantime, many schools will be viewing their data with some suspicion.
* 2023 Y6 cohort: pre-Covid KS1 assessment, post-Covid KS2 tests. 2026 Y6 cohort: post-Covid KS1 assessment; KS2 tests 5 years after pandemic.
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