Trebla said:
I don't see why the raw marks have to used for scaling. Since aligning is done to supposedly even out the distribution of marks in comparison to previous sucessive years, why not use that mark, since it is more "fair"?
Aligning ensures that the marks awarded are consistent with the performance bands and the standards that have been set for each course. It has the effect of compressing and inflating the distribution of raw marks, which typically spans a range of 0 - 100, to the range of 50 - 100. This means that students who might have had different raw marks could end up with the same aligned mark (and would thus be ranked the same when they shouldn't be). The UAI is all about ranking students, so raw marks are used to ensure that they can be ranked properly.
Trebla said:
Plus, I've noticed on the UAC website (
http://www.uac.edu.au/pubs/pdf/2004-Table-A3.pdf) that the scaled mark in MOST cases is lower than the HSC mark, but for some courses like Mathematics Extension 1, the 50th and 25th percentiles have scaled marks higher than their HSC mark, but the 99th, 90th and 75th percentiles have their scaled marks lower than their HSC mark. Why is that the case? Shouldn't higher percentiles have higher scaled marks in relation to their HSC mark compared to those in the lower percentiles? Is this where capping comes in?
As Rench said, you can't compare aligned marks between courses. But more importantly, you can't even compare aligned marks with scaled marks. Aligned marks are derived from raw marks, and scaled marks are derived from raw marks, but both derivations use completely different procedures - it can be meaningful to compare aligned marks with raw marks (to examine the effect of the aligning process), and to compare scaled marks with raw marks (to examine the effect of the scaling process), but there is no value in comparing aligned marks with scaled marks.
Trebla said:
Hold on, so does that mean capping only occurs in subjects that offer courses with specific levels?
The term "dumbing down" has been abused a little - you're right, the term does imply that there are higher level courses which were more appropriate and could have been taken. In the past, the maximum scaled mark in every course was guaranteed to be 100% whenever the maximum raw mark was 100% (i.e. the Technical Committee on Scaling would never cause a mark of 100% to be lowered). Furthermore, the Board was in the practise of awarding a mark of 100% to the student(s) who topped the course.
As a result, some students who were capable of taking the higher level English courses would in fact choose the lower level English courses - as they're taken by 'less able' students, it was easier for them to top (or come close to the top of) the course, and hence to be guaranteed a scaled mark of (or close to) 100%. This is usually what is referred to as "dumbing down".
However, it's not restricted to subjects where there are graded courses of varying difficulty. A student bent on maximising their UAI could opt for a course taken by a candidature that was far below average (indicated by a low scaled mean) with the hope of ranking first and being guaranteed that elusive 100%.
To avoid all of this exploitation, the Technical Committee decided to allow the maximum scaled mark to vary between courses, linking it to the overall academic ability of the candidature (the scaled mean) and the variation of that ability (the scaled stdev). As a result, courses with less able and/or less variable candidatures have a maximum scaled mark that is lower than 50 - thus removing the advantage that could be obtained by "dumbing down" under the old system.
Hope that makes sense.
(My personal view is that the scheme didn't go far enough - candidatures of low ability/variability now have lower maximum scaled marks, but candidatures of high ability/variability don't have higher maximum scaled marks. They're 'capped' at 50. I believe that if the maximum scaled mark is to be allowed to vary between courses, it should truly be allowed to vary; even above 50.)