The moderating process*:
For each of your subjects your school will send the BOS a list showing the school marks attained by each student. The BOS doesn't care what these marks are. They want to see a) the ranks of each student and b) how large the spaces between each student are.
This happens before your HSC exams and you have the opportunity to verify these results before they're sent away.
Then you do your exams. During marking, you are marked as an individual. Your papers will be in a bundle with all the other scripts from your exam centre but this is for organisational purposes. No one else's marks are a factor in your exam score.
The BOS then takes your exam score and the exams scores of everyone else in your cohort and finds the average. This average is then transferred to the set of internal marks and becomes the central point. The BOS will assign the top internal student the top exam mark and the bottom internal student the bottom external mark (though not if the bottom mark is excluded for reasons given below). Then they will assign internal scores to the other students in the cohort which preserve the group mean and the relative gaps between each student as per the documentation the school sent off.
The average of your internal and external marks then becomes your final HSC score.
There are several rules designed to protect the group mean, including the exclusion of significant low outliers and anyone with successful illness/misadventure appeals. This is so that others aren't unfairly impacted.
The ideal scenario is that a school is able to send off documentation showing even gaps between students and then that cohort backs it up with a high exam average.
(*if I've made any errors here, sorry. Feel free to correct.
Also, scaling =! moderating. Scaling is done later by UAC and has nothing to do with BOS.)
Regarding school ranks:
School ranks are a past-tense measurement. There's no way to guarantee that just because a school was ranked ~300 in 2009 they won't be ranked ~200 in 2010. So school ranks are a guideline only, not cast-iron. Rather than past-tense school rankings, what matters is that all-important exam average of your cohort. That's what will end up influencing your internal mark. So the idea is that after your trials are over and you're finished competing against each other for rankings, the cohort is better off working together to make sure everyone has the tools to succeed in the exam. Those last few weeks (and then the holidays as well) are a really good time for cooperation, particularly in schools which have had lower rankings in the past. You don't have to devote time to the group at the expense of yourself but group learning can often be very beneficial, even if you're already at the top of the class (explaining or teaching things cements the concept in your own head).
Of course if you've come first in everything you don't need to worry about any of this because as long as you continue to come first in the exams you don't feel any of the effects of moderation. But it's still good to consider the rest of the cohort just in case you screw up your exam.
