Can someone help please? I was under the impression that everyone got their scores multiplied by some magic multiplier for standardisation. This multiplier is determined by the month of birth within the year. Am I right?
Yes and no.
Yes, there is a magic multiplier, but rather than being the same figure each year, calculated just on the birth month, it's calculated by looking at the birth months (or date) for all of the pupils who have asked to have their scores shared by that individual school for that exam (aka 'the cohort'). Hence it will be different each year for the same school, and likewise each school will have a different multiplier in the same year.
This is one of the reasons that it's difficult to calculate positions of children who did not ask for their results to be shared but then decide after the result have come out that maybe they would like them sharing. To do so would mean that that child then needs to be added in to the calculation for that school, then the new weightings re-applied to all the pupils, and new ranking positions issued to all the pupils - which would be unfair on those who had made their secondary choice based on the original rankings.