As every NSW school student and parent knows, the Higher School Certificate is a relative ranking, with 80 meaning that you beat 80% of your cohort. Each year’s students are compared to their peers.It doesn’t take a 4 unit maths student, therefore, to puzzle at the claim in today’s SMH that "HSC’s best are getting even better". Since we compare every year’s students against one another*, how could this be possible?
The answer turns on the meaning of "best", which is apparently defined by the SMH to mean the share of students scoring above 90% in one or more courses. In other words, the cross-course grade correlation has fallen. This might be good, or it might be bad – but I’m not sure I’d categorically class it as "getting better". Of course, the flipside is most likely that the share of students scoring below 50% on one or more courses has also risen.
* In fact, the average UAI has probably fallen a bit, since the UAI is your rank not only among test-takers, but among the age cohort. So the average UAI actually given is slightly above 50, but as year 12 completion rises to 100%, the average UAI will fall to precisely 50.