I will try to give an example from my first ratings I tried for its these I have been trying to improve, and for me it has to be simple I cant do complicated when it comes to excel, my basic knowledge of maths is add, subtract, divide, and times.
First I gave each class a base score, but as i write this i am wondering if all should start with a base score of 100.
Horse WE NEVER STOP,last OR 92, ran in a class 2 which i gave a base score of 91.67, class 2 class band is 86-110. my first sum is Base score 91.67+(last OR 92 - lowest class band 86)/(highest class ban110-lowest class band 86)then x 10 which give me a score of 94, next might be a mistake because I have been looking at ways i can rate form, and have not found anything simple as yet so I use fineform and add to the 94, in this case 5 wass added giving 99. next weight last time weigt in lbs was 122 and the weight carrying now 135, subtract the difference 13 the difference is divided by lbs per length the race was over 5f and the lbs per length was 3.35. 13/3.35 is 3.88 this is added to the 99 to give me a final rating. WE NEVER STOP SCORED 103.
Thats where I started and have been trying to improve on without too much success. Simple Maths, and for me it has to be simple.