How the IITs said they calculated the cut-off marks for JEE 2006:

nOver 2 lakh general category students appeared in the three papers: physics, chemistry and math

nThe average of the marks scored by all these students was calculated separately for physics (P), chemistry(C) and math (M)

nThe standard deviation — a statistical quantity that measures the “spread” of marks on either side of the average — was computed separately for physics (SDP), chemistry (SDC) and math (SDM)

nThe cut-offs for the three subjects were determined in this way — physics: P minus SDP; chemistry: C minus SDC; math: M minus SDM (that is, the average minus the standard deviation, individually for each subject) *

The IIT cut-off marks in 2006 (obtained under RTI Act):

nPhysics: 48, chemistry: 55, math: 37. A further aggregate cut-off was set: 154

What aggrieved parents did:

nObtained marks — in all three subjects — of all students who had cleared the cut-off in physics (even if they might not have made the cut-offs in the other two subjects)

nObtained similar lists for students who had cleared the chemistry cut-off (but may or may not have cleared the other two cut-offs) and math cut-off (but may or may not have cleared the other two cut-offs)

nMerged the three lists, and removed duplication (of students who cleared more than one cut-off) to come up with a consolidated list of over 32,000 candidates. These candidates automatically included all those selected — that is, those who cleared the aggregate cut-off — and also all those who cleared one or more subject cut-offs but not the aggregate cut-off

nCalculated the average and standard deviation for each subject from this consolidated list of “toppers”

nThen came the shock: The cut-off marks, calculated by the method disclosed by the IITs from the list of toppers, were: physics: 22, chemistry: 26, math: 24

nAnd the IITs’ official cut-offs should have been even lower. Because their database included the “non-toppers” as well

The significance:

nApart from the around 6,000 students called for counselling, several hundred of the other toppers who had made the IITs’ aggregate cut-off but missed one or two of the subject cut-offs would have made all the subject cut-offs calculated by the parents

* The same process was used to calculate the cut-offs for SC/ST candidates