Well the idea that selective school kids get bonus UAI points from scaling just isn’t true. There’s just a lot of complex mathematics behind it, the point is to standardize all the internal marks from different schools to make it (theoretically) fairer for everyone. I don’t think the BOS really reveals exactly how it’s done but here’s the general idea.
Scaling is done twice, once by the BOS, to change the mean and standard deviation of your year group’s internal assessments to that of the external exams. Your internal marks may change, but your rank will remain the same. As an example, say your school mean for subject X was 80 with a standard deviation of 5 and u got 85. So you are one standard deviation off from your mean. In the external exams, your year group gets a mean of 84 and standard deviation of 7. This would mean your internal mark will get scaled to around 91. This tends to be the case with selective schools as they either mark harsher or have harder exams (although this isn’t always the case) and so the BOS will have to scale up the internals. Anyway, these scaled scores are what you see from the BOS. (I have no idea btw, how they scale raw external marks).
The second set of scaling (internal and external marks) is done by UAC who will take these results and scale according their own standards. This means for example, a 95 scaled mark in EXT2 Math will be worth MUCH MORE to your UAI than a subject like Legal Studies. I think you can actually order material from UAC which goes thru in detail how certain subjects are scaled.
In terms of the SAM, you will need to feed in your scaled marks (or at least what u expect will be your scaled marks). I go to James Ruse, so a lot of that has already been done for me (i.e. the school scales the raw marks to the previous year’s BOS scaled marks so they are usually fairly accurate). As lala2 was saying, this is actually quite a good measure of your scaled marks. What you could do is, find your rank for every subject, find some from the grade who did the HSC the year before and ask their scaled mark. Unless your grade is a lot better or worse than the grade above, this is one of the best ways to get your scaled marks.
James Ruse actually does UAI estimates (I think NSG does too) in a very formal manner. They scale internals to the marks from the grade before and scale again using information from UAC. It doesn’t actually go on your report; rather it’s meant to give you an idea of where you are. I find that the Ruse estimates tend to be lower than the SAM scores. Anyways I hope I’ve made things a little more clear.
Jeremy