target setting

The difficult area of target setting for maths is being tackled at our
school and I wanted to know the pros and cons of various methods. What
degree of accuracy to these methods carry:
KS2 SATS APS to GCSE?
KS3 SATS APS to GCSE?
Yr7 CATs to GCSE?
KS3 Level to GCSE? eg for a 7b expected grade is A.

ALSO
Where can I find official figures matching levels with grades
eg 80% of pupils improve by 2sublevels a year (eg 4c to 4a)
eg 80% of pupils achieveing a &b at KS3 gain a GCSE grade A

I realise there's alot of questions here but any help is appreciated
Thanks :-)
Chellly

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