From memory, there was a bit of a political drama going on with 4 Unit maths scaling in 1989/90. The perception was that the scaling algorithm resulted in 4 Unit maths scaled marks being inflated. This was thought to be a consequence of them not being included in the initial 2 Unit scaling or 3 Unit scaling. Rather they are slotted into the 3 Unit group after the interative scaling process. Anyway in 1989 4 Unit students, in my opinion, were ripped off. The situation has now been pretty much resolved.