Last night I spent almost three hours reading [the full Ofqual statistical paper on subject comparability at school level in the UK](https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/486936/3-inter-subject-comparability-of-exam-standards-in-gcse-and-a-level.pdf). I am not a statistician (obviously) but I've set out below my working through of what they have presented and the underlying assumptions that they have made in