ATAR Notes: Forum
VCE Stuff => Victorian Technical Score Discussion => Topic started by: mystikal on June 05, 2008, 02:58:56 pm
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Man ive read all the topics on the SAC rankings and stuff but i dont get it, ive read the threads they make no sense to me so ive decided to make a little simulation and u guys tell me what is happening.
FIVE PEOPLE are doing VCE English 3/4 (Or any other subject where SAC marks are worth 50% and the exam is the other 50%)
Person A= In unit 3: A+ [rank 1] unit 4: A+ [rank 1] exam:B+[rank 5,his girlfriend broke up with him :'( ]
Person B= In unit 3: A+ [rank 2] unit 4: A+ [rank 2] exam:A [rank 3]
Person C= In unit 3: A [rank 3] unit 4: A [rank 3] exam:A+ [rank 2]
Person D= In unit 3: B+ [rank 4] unit 4: A [rank 4] exam:A [rank 4]
Person E= In unit 3: B+ [rank 5] unit 4: B+ [rank 5] exam:A+ [rank 1, this time he wasnt stoned ;D]
Please predict the study scores for me so i can understand and explain it as well =[ im a bit thickheaded
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Person A would end up getting A+ A+ B+ (probably mid-high 30's SS)
B - A+ A+ A (high 30's, maybe 40's)
C - A A A+ (high 30's, maybe 40's)
D - A A A (high 30's)
E - B+ B+ A+ (mid-high 30's)
You may notice that each person took on the exam grade that was equivalent to their rank, regardless of who got the exam grade. E.g. person ranked 1 got the highest exam score (person E's) as their coursework scores and then kept their own exam score. This is a crude example, but it's more or less accurate.
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Ok but how come the guy who got B+,B+ for units 3/4 and A+ for exam i heard if u do really well in exam u can get 40 RAW == wells dats wat ive been told, because im in a situation right now where i probably getting an A for unit 3 and i was hoping if i do well next unit and get an A+ and for Exams get an A+/A i wud get 40+ SS == if not mah dreams are gone == o yea its just history so yea == in year 11 doing 3/4 history =[
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its not impossible to do, but your performance in the exam does not change your SAC rankings [whatever the case may be].
so if you are ranking 5th [for example], you'd hope the fifth ranking exam score [hence moderated external score] is high.
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What would be an approximate SS for someone who got A+ A+ for sacs (rank 1), but an A on the exam?
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That was the situation for me in Legal last year ( A+ A+ A) and I got a 40. That would probably be the best case scenario. I think 38,39 would be more common
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i thought your ranking gets boosted with a high exam mark - doesn't vcaa treat you like an exception to your school's results if your exam result is (for example) an A+ when your ranking is in the middle of your cohort?
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There is a page on statistical moderation on the VCAA website explaining it (though poorly). Essentially, your exam mark will influence your SAC mark. This occurs because your SAC mark is what undergoes moderation. This means that your grade in you cohort translates to be the grade you would have gotten regardless of what school you went to. look on the VCAA website to see it fully.
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i thought your ranking gets boosted with a high exam mark - doesn't vcaa treat you like an exception to your school's results if your exam result is (for example) an A+ when your ranking is in the middle of your cohort?
from my knowledge, the only cases when your results are removed from the cohort is when you apply for derived exam scores, otherwise your ranking stays the same.
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Your SAC ranking will NOT change no matter what your exam mark is. You DO keep your own exam marks.
Students can be excluded if they: miss a SAC, do much worse on their exam than their sac marks would indicate, get a derived exam mark, change schools halfway through the year (and i think a few more but i've left the info at school)
Your exam mark (and other information such as your GAT score) will then be used to determine an external score. This external score is basically an indication of what anyone who received that exam score got as their coursework (SAC) score across the entire group of students doing that subject.
These external scores are then ordered from highest to lowest against your cohorts rankings (ie SAC rankings given by the teacher) and locked in at particular points (max, upper quartile, median, and lower quartile) and a quadratic formula is then applied to align your cohorts given SAC marks against the calculated external marks. Once the quadratic formula has been decided, it is applied to ALL students in the cohort, including those initially excluded.
(in simple terms, the highest ranked student gets given the highest external mark which was calculated from the highest exam mark which may or may not have been their own exam mark)
http://www.vcaa.vic.edu.au/vce/publications/vcebriefpresent30-04-08.pdf
the last few pages of this have three examples of different cohorts of the same subject. The first is a 'small' (<16) moderation group so is only locked in at the max and median. this is an example of a group that had 'harder' sacs and so all of their sac marks were standardised up.
the second is a 'large' moderation group and so is locked in at 4 points. this is an example of a cohort which generally had 'easier' sacs (or perhaps they weren't very good at sitting exams) and so their sac marks were standardised down.
the third example is a common question of what would happen in an average to low cohort with one brillliant student. In it you can see (hopefully) that the high achieving student is not disadvantaged by a lower performing cohort.
In short, you want to achieve the highest ranking you can so you aren't disadvantaged by a poorly performing cohort. You also want well designed, medium to hard level sacs that dont result in all the marks being bunched together.
I hope this has made some sense. I may need to edit later.
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This is really interesting
(http://i78.photobucket.com/albums/j117/sxy_grk_star/Untitled-1.jpg)
Can someone explain to me the calculations they have got going on there...
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thank you very much chem-nerd :)
costa:
http://en.wikipedia.org/wiki/Normal_distribution
basically, everyone's scores gets entered on a computer, it then runs a statistical model and "normalise" the scores so it fits nicely to the bell-curve, producing "standardised score" as the Z score in normal distribution, and the sum of GAs then translates to a study score with a bell curve at mean=30, sd=7
you did it in Methods last year :)
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Bahahha Yeh I did LMAO I didnt do too badly in this section either. (i think about 50% LOL). I was actually talking about the weighted score but just realised how obvious it is. Stand score X weighting (eg. 0.25) lol soo dumb
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hrmmm interesting picture...dont know how they work those out but looks complex...
anyways well thanks for the help == im still abit mystified but i get it
That you keep your own SAC rank
and
You keep your own EXAM score
but i want to know is for the GA1 if im averaging an A and i am approx in the middle cohort or mayb a little above the average like 15-25th(dont know exact) out of 60 students is it still possible for me to get a 40+ SS if i try for GA2 and do alright for the exam if so. Can u tell me the minimum marks(grades) i would need to fufill this for the next 2 GA and does the GAT contribute to the scaling by a bit? Yea sorry if i seem stupid but its my first time experiencing VCE and i want to understand before next year where all my subjects do count as well.
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o yea by the way please explain that picture !!! looks interesting ;D
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only SAC ranking and exam score are absolute in your SS calculation
as for the actual GA scores for SACs, that depends on a few things:
1. how the state cohort performs
2. how your cohort [class] performs
your SAC ranking will correspond to an "external" score that is moderated on the state's performance in regards to GAT performance in your cohort
[basically, top SAC ranking approximates to top exam score]
hence, your "i've got an A+ in my SACs woot" is quite meaningless until you come to tell us that "our cohort average at B+ exam performance with heaps of A+ scores" or something like that.
the actual GA outcome depends on many things, this is the thorny process of statistical moderation [i have lost count how many times I've explained this, less other people doing the explanation, hurry up viki so we can have a FAQ!!!! :P]
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I saw that somewhere, just can't exactly remember where :P
But that's weird as, he got an A for the exam and got 42? but the person got A+ for all and got 40. wtfbbq?!
It's showing that the SAC mark is more important? :S
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no - look at what the A+ range is. it shows that student C was at the higher end of the range than student B for GA1 and GA2 and only slightly lower in GA3
the weighting is still the same for both students but whereabouts their scores fell in the range was much different for two of the graded assessments
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In physics (at the end of Unit 3) I think I'm narrowly in 2nd. Just say I managed to finish 1st in Unit 4 by a larger margin. What would this mean for the 'absolute' SAC ranking. Is it separate for each Unit, or an overall one?
Thanks.
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For science subjects and accounting the SACs for the WHOLE year are ranked together. For chemistry (and the others - I think) the SACs are out of 100 for each unit so the GA2 mark will be out of 200.
So your ranking will be calculated from ALL of your SACs over units 3 and 4.
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Does anybody know how the languages work? I mean with the orals and all...