It is pointless comparing all your GCSE results to all your AS-Level Results because it is your GCSE results in the subjects you took your AS-Levels in that matter.So I want the UMS results for your GCSEs in the subjects you did your AS-Levels in and your AS UMS for those AS Levels for comparison converting the difference between them to a percentage-comparing simply grades it is very hard to determine the difference in difficulty of GCSE and AS-Level. This may be tricky for subjects you didn't do that subject in so you will have to exclude them and also for Additional Science average your results in the Science you took to A-Level and add it on to count for Unit 3 and add your Additional Science ISA on.Students who are awaiting AS Level results please feel free to add your UMS predictions.For Linear GCSEs, please apply the UMS rules to your raw mark.
I will give my GCSE UMS and AS UMS predictions as an example:
GCSE Maths A*(295/300) AS Maths Prediction-A (292/300) -3 UMS=-1%
IGCSE Further Maths A^(174/175 raw mark),A^ is generally worth 100% GCSE UMS applying UMS rules so (300/300) AS Further Maths Prediction-A (283/300) -17 UMS=-5.67%
GCSE Physics Unit 1-A(84/100),GCSE Physics Unit 2-A*(90/100) and GCSE Additional Science ISA-A*(95/100)-this was actually the same ISA as for Physics so is good to use for this calculation average of Unit 1 and 2=A(87/100) so for this gives GCSE Physics-A(356/400) and AS Physics Prediction- A(249/300)=-6%
GCSE Geography A(350/400) AS Geography Prediction B(156/200)=-9.5%
average UMS difference=-5.54%(as said before exclude any subjects in this average where you can't account for GCSE UMS).