@SeasonFinale... Referring to GCSE, AS and A level only... yes, you are of course once more right - teachers certainly can work out what % of grades corresponds to the appropriate historic average (assuming that it is this average that is 'the right answer').
But it's what happens next that is "interesting".
When the historical average is applied to this year's cohort to determine the number of this year's candidates to be awarded any grade, the result is likely to be a fraction. But candidates come in whole numbers. So all those fractions have to be rounded.
If everyone rounds strictly in accordance with the rules of arithmetic, rounding down as well as up, then the all-school aggregate, as computed by the exam board, is likely to comply with a policy of "no grade inflation" (if that policy is enforced, which once again I don't know).
But if more than half of the schools round up for the higher grades (and especially if any add, say, 1 more, as might be 'encouraged' by virtue of the year-on-year variation in the numbers from which the average was computed), and down for the lower grades, then the policy of "no grade inflation", as applied to the whole-school aggregate, will be blown sky high. www.tes.com/news/exams-gcse-alevel-grading-issue-risk-concern
I wonder to what extent FFT Education Datalab's results can be explained by the well-intentioned 'optimism' of schools that rounded up, and submitted numbers for the higher grades a bit above the average, but still within the upper variation limit, and without any 'game playing'? For if this is what has happened, the outcome will be catastrophic, and deeply tragic.
To my mind, the fundamental error was the failure of Ofqual to provide all schools with a spreadsheet, or equivalent on-line tool, to do all these computations in exactly the same way, using exactly the same rules for rounding, at every school. The data required is simple: for each subject, the number of students awarded each grade in each of the relevant prior years, and also this year's total cohort. The spreadsheet would then do all the rest, and result in a "recommended distribution". I would also have added an opportunity for schools to make adjustments, to recognise 'outliers' and 'special cases', and to compile the corresponding evidence to be presented to the boards as required.
By ensuring all schools do the computations in exactly the same way, this protects the 'level playing field', and ensures fairness - as far as the policies are fair.
Ofqual could have made such a tool available on 21March, the day after Gavin Williamson's statement. But they didn't.
This is not the wisdom of hindsight. It was a choice open to Ofqual at the time; a choice they did not take. Nor is this in any sense novel. The spreadsheet is not difficult to design, and the use of exactly the same process and model is standard good practice in relation to any situation in which a number of independent entities are required, in essence, to do the same thing, but with different data sets.
But that didn't happen. And we are all living with the consequences. Oh dear.