Simple way to understand how cohort affects your mark (1 Viewer)

[A1P]

We all know that BOSTES uses Quadratic Interpolation to moderate your school mark, but it's difficult to visualise how it works. A simple way to approx is like this: Your Internal mark's relative position in between the top & bottom Internal marks determines your Assessment mark in between the top & bottom Exam marks.

IOW, say you are halfway between the top & bottom Internal marks, no matter your rank, you get the halfway mark between the top & bottom Exam marks as your School Assessment mark.

Can stop there if you're happy enough with this approximation. To be more correct it needs to plus/minus a correction for the reason that [the total pool of your cohort's Assessment marks] must equal [the total pool of your cohort's Exam marks].

In summary,
Your HSC mark (before scaling/aligning) = [Exam mark + Assessment Mark] /2

1. Exam mark & Assessment mark each affects 50% of Your HSC mark => They are equally important

2. Your relative position between the top & bottom Internal marks is more relevant than your rank

3. The total pool of your cohort's Exam marks affects whether your Assessment mark is corrected up or down i.e. after allocating the top & bottom marks to these two students the rest of the pool is divided up proportionally to the others. The bigger the pool the bigger your share (that's how cohort affects you) so don't worry about a few doing poorly if the cohort as a whole does well.

Will discuss & verify this method in the next post if you're interested.

 

[A1P]

The common saying that if you rank say 10th Internal you get the 10th Exam mark as your Assessment mark, does not work out well if the gaps are uneven. As in this BOSTES doc <http://www.boardofstudies.nsw.edu.au/hsc-results/moderation.html> the 2nd exam mark is 80 but 2nd assessment mark is 77.

In the example Exam Marks: 92 - 80 - 72 - 60 - 55 - 50 (total 409)

By the rank method Assessment Marks would be same but
by BOSTES Quadratic Interpolation they are: 92 - 77 - 74 - 59 - 57 - 50 (total 409)

If by my simple method described above: 92 - 76 - 73 - 60 - 58 - 50 (total 409)

Not bad for an approximation yet much simpler to comprehend.

 

[si2136]

What is the difference between your rank and the relative position between the top & bottom Internal marks?

Are you talking about the differences between the marks within the cohort that defines how 'strong' the cohort is which can affect our HSC mark?

 

[A1P]

What is the difference between your rank and the relative position between the top & bottom Internal marks?

The relative position is in terms of your numerical mark vs the top & bottom marks.

For example your mark of 85 ranks 2nd between 95 top and 45 bottom: you're 10 marks off the top in a range of 50 => 20% down.
If your mark is 90 instead but still ranks 2nd, you are only 10% down thus get a better Assessment mark (vs 85) despite same 2nd rank.

 

[A1P]

Are you talking about the differences between the marks within the cohort that defines how 'strong' the cohort is which can affect our HSC mark?

There are many different scenarios but let's pick one to explain.

To illustrate let's fix the top to 95 & bottom to 45, both Internal and Exam. If all the ones in between are top heavy in Internal but bottom heavy in Exam, the result is they interpolate well onto the Exam mark range but the total Assessment mark pool will exceed the total Exam mark pool. Thus everyone except top & bottom need to be corrected down.

By the same token, it works the other way if all the ones in between are bottom heavy in Internal but top heavy in Exam.