CSSE Standardised score calculation:
Say if a child gets 40 marks in English and 40 marks in Maths then standardised score is 321.193566
English Marks Eng Avg Eng SD
40 33.174 8.665
Maths Marks Maths Avg Maths SD
40 38.349 10.709
Eng Std Maths Std
111.8165032 102.3125409
TotalMarks CSSE Score
80 321.193566
English Std score =((40-33.174)/8.665*15)+100 = 111.8165032
Maths Std score =((40-38.349)/10.709*15)+100 = 102.3125409
Total Score = =1.5*(111.8165032+102.3125409 ) = 321.193566