QCAA ATAR Scaling Report - How does QTAC do scaling in QCE?

Are you a QCE student? And are you confused about the scaling system for QCE? This article dives deep into exactly what the ATAR is, how to choose your subjects and what "polyranks" mean!

2 months ago   •   7 min read

By KIS Academics
Photo by Patrick Tomasso / Unsplash

Are all QCE subjects created equal? Should you choose subjects to please the scaling equation? Answers to these questions and more will be discussed below, so keep reading!

What is the ATAR?

As you may know, the ATAR system creates a number for each student from 0.00 to 99.95 in 0.05 intervals based on their academic achievement in QCE subjects. Each QCE subject has a total possible raw score of 100, and the best 5 subjects for each student are considered in the ATAR calculation. However, the ATAR score isn’t a 1:1 reflection of your academic performance. It is a percentile that ranks you against ATAR students in the Grade 12 cohort of your state for the year you graduate. For example, if you’re from Queensland, receiving an ATAR of 80 indicates that you ranked in the top 20% of Queensland’s Grade 12 ATAR student cohort that year. I specifically say “ATAR student cohort” as not everyone who graduates grade 12 is eligible for an ATAR. Thus, keep in mind your percentile rank is generated only out of those who did get an ATAR.

From this description of the ATAR, you might notice two variable factors influencing the ATAR; the combination of the top 5 subjects, and the performance of your state’s ATAR student cohort in the year you graduate. Let’s break down how exactly these factors affect your ATAR.

Inter-subject scaling

In QCE, there are over 50 subjects to choose from, meaning there is a huge number of subject combinations. This makes ranking students against each other challenging, as certain subjects may be easier to do well in than other subjects. Thus, simply comparing students’ cumulative raw scores does not necessarily reflect their academic ability accurately.

This is where inter-subject scaling comes in. Scaling is a method of objectively comparing raw scores from different subjects. It does so by converting raw scores into a common scale.

The process is as follows:

1.  Initial scaled scores

A student’s raw score in a subject is used to rank them against all other students who took the same subject (even the ones not eligible for an ATAR).

2. Polyranks

A polyrank is the average of a student’s top five QCE subjects based on their scaled scores. This number is generated for all students

3. Individual raw scores

A raw score achieved by an individual student in one of their top five QCE subjects is selected. This raw score is then used to find all the other ATAR students that scored that same raw score in that subject. Once we have a pool of these specific students, their polyranks are averaged. This average becomes the next scaled score. This process of averaging polyranks of students who scored the same raw score in the same subject is repeated for every ATAR student’s top five QCE subjects.

4. Iterations

The scaled scores produced in step 3 cause student polyranks to change. Thus, this process of averaging the polyranks of students with the same raw scores in a subject will repeat until the estimated scaled scores start to stabilise, and each repetition has a negligible change in scaled scores.

Here's an example to illustrate:

This table illustrates how the raw scores of a hypothetical ATAR student are converted into scaled scores through iterations.

 

 

Scaled scores

Subjects taken

Raw Scores

Initial

First iteration

Final iteration

English

86

87.6

88.2

91.11

Specialist Mathematics

93

94.5

95.3

98.53

Economics

84

86.1

87.7

93.74

Modern History

83

83.8

84.3

87.43

Dance

100

97.4

96.3

82.55

Chinese

95

94.6

94.1

90.81

Polyrank

 

92.04

92.32

92.324

NOTE: The final iteration scaled scores are taken from QTAC’s Scaling report in 2021. The initial and first iteration scores are only estimated to illustrate how the scaled scores change with each iteration and should not be considered accurate.

As you might notice, this student scored the highest raw score possible in Dance, but this subject ended up having the worst scaled score in the final iteration of the scaling process. Thus, the scaled score for Dance would not be considered in their ATAR. Conversely, Modern History had the lowest raw score of 83 out of the six subjects, but its scaled score ended up being 87.43, which brings it up into this student’s top five QCE subjects based on scaled scores.

Finally, ATAR is calculated by first filtering out students who don’t meet eligibility for an ATAR. Then, a Tertiary Entrance Aggregate (TEA) is used to allocate students into ATAR bands. The process of TEA is separate from scaling, but if you are interested in learning more about that, you can click *here* to see a report by QTAC which outlines this process. This report also goes into more detail about the actual mathematical processes behind scaling and ATAR calculation in general.

Should you choose subjects that scale well?

The short answer is no. This is because no one can predict how a subject might scale because no one can accurately predict how everyone else in your cohort will perform (especially on external assessment). So, choosing subjects because they scaled up in the past doesn’t guarantee a high scaled score in the year you do Grade 12. Additionally, scaling will not give you any “free” ATAR points! Scaling is a method to fairly compare raw scores from different subjects by converting those raw scores into a common scale. Please do not expect scaling to pull a poor mark in a typically high-scaling subject; it will only reflect a poor mark as what it is on a different scale!

Instead of picking certain subjects based on scaling, you should pick subjects that you enjoy studying! If you actually like learning a subject, you’ll be more motivated to listen in class, revise the content and actually learn well (which is sort of the whole point of school)!

Should you only focus your time on five subjects?

The answer again is no. As you can see from the example scores in the table above, it is possible for your best-scoring subject to not count towards your ATAR at all! Additionally, to get your high school diploma (i.e. QCE), you need to pass a certain amount of units and you must pass certain subjects to meet its requirements. So, intending to do very poorly in one subject for the sake of five others is a very risky business; it might even cost you your QCE!

The alternate recommendation is the same as before – pick subjects you enjoy learning, or at the very least, do your very best in all the subjects you study! Because in the end, exactly which subjects count towards your ATAR is unknown until the day you receive your ATAR (by which point it isn’t much you can do).

QCE scaling in 2021

Now we’ll go into how to read the QTAC ATAR report, which you can find *here*. It has a lot of information about the cohort that graduated that year, as well as some more explanation about the ATAR, but most people are interested in how subjects are scaled, so let’s get into it!

On page 12 you’re hit with a wall of numbers spanning several pages. The heading of this long table tells you that the leftmost column displays the General subjects, the next column indicates the type of results shown and the right columns are a series of percentiles. This means that 99% of Economics students scored a raw score of 96 or less. Conversely, 1% of students had a raw score higher than 96. The number below this raw score is its scaled equivalent – for 2021, a raw score of 96 in economics was converted into a final scaled score of 97.67. You might also notice some blank rows in the table, and this is because less than 50 students took that subject in 2021.

Here are some quick facts about 2021’s subject scaling:

The best scaling subject was Specialist Mathematics, with a raw score of 88 being equivalent to a scaled score of 97.78 (an increase of 9.78 points).

The worst scaling subject was Dance, with a raw score of 100 being equivalent to a scaled score of 82.55 (a decrease of 17.45).

A surprising scaling result came from Geography, which consistently scaled up (e.g. raw 84 scaled to 90), unlike last year, where it scaled down at its 99th percentile.

English scales up generally (e.g. from a raw 77 to a scaled 84.57) but scales down when raw scores get higher (e.g. raw score of 97 is equal to a scaled score of 95.66).

Literature follows a similar pattern to English, generally scaling up (e.g. raw 88 is scaled to 93.19) but scales down for higher scores (e.g. raw 99 is scaled to 96.99).

Mathematical Methods scales up generously except for the 99th percentile, where a raw 99 scales to a 98.24 (which is quite a minor difference).

Specialist Mathematics consistently scales up, where a raw 78 scales to 94.99 (an increase of 16.99 points).

Economics consistently scales up, with a raw 96 scaling to 97.67.

Physics generally scales up well (e.g. raw 89 scaling to 95.22) except for its 99th percentile which scales a raw 99 into 98.28.

Chemistry consistently scales up, with a raw 94 scaling into a 97.25.

Chinese consistently scales down, with a raw 100 scaling into 92.93.

Again, you can view the whole scaling results in the QTAC ATAR report, which you can find *here*.

TLDR; Scaling helps compare raw scores from different subjects in a fair way by converting them all into a common scale. This is done through a process of ranking students and averaging scores until final scaled scores are produced. The absolute amount that a raw score might scale up or down by changes every year, and it is not possible to accurately predict this. It is highly recommended that you choose subjects that you genuinely enjoy, as this increases the likelihood of you studying well and ultimately performing well. There is no way to “game” the ATAR system, it’s designed so it can’t be gamed :)

If you’d like personalised, one-on-one help with your QCE studies, look no further! This link will show you KIS’s list of amazing QCE tutors who’ve been through the ATAR system with flying colours!

Alternatively, if you would like to get affordable, quality study resources, check out this link! KIS has concept videos, worksheets, quizzes, and more for a range of QCE subjects, tailor-made for students, by KIS’s own high-achieving tutors!


Written by KIS Academics Tutor for QCE Mathematical Methods, Chemistry, Physics, Biology and Psychology, Hoi Yan Lee. Hoi is currently pursuing a Bachelor of Science Major in Psychology at UQ. You can view Hoi’s profile *here* and request her as a tutor.

Spread the word

Keep reading