Can I Score a High Atar With Low Scaling Subjects?

A commonly pondered question by many students is whether their subject choices made at the end of year 10 would preclude them from getting a ‘high ATAR’. Now, what does ‘high ATAR’ mean to you? What constitutes a high ATAR to one person will differ to the next as it is a subjective question relative to one’s ability and expectation, amongst other things. For argument sake, let us suppose that a ‘high ATAR’ is anything above 99 (understandably this may be more appropriately deemed a ‘very high ATAR’ to some). Now therefore the question becomes ‘can I still get 99+ with relatively low scaling subjects?”

The short answer is: yes, of course you can!*

***The long answer:**

You may already have at least a vague idea of how the **HSC scaling** process works, so you may be able to understand that there is theoretically some trade-off between how well a subject scales, and how difficult it is (if there was such a thing as an objective measure of subject difficulty). What this implies is that if your HSC portfolio is mostly low scaling subjects, your level of achievement within each subject would have to be comparatively higher than if your portfolio consisted of mostly higher scaling subjects. What this may mean generally is that 10 units worth of 90s (HSC aligned marks) in low scaling subjects may result in the same ATAR as 10 units worth of 80s in higher scaling subjects.

Let’s look at some hard numbers to support our thesis. Each year, the UAC publishes a set of scaling statistics in Table A3, as part of each year’s annual Scaling Report. The latest years of table A3’s are available on the UAC website, or at: http://www.duxcollege.com.au/hsc-scaling-statistics-i-34.html. Table A3 compares all available HSC subjects in terms of several statistics, the important ones being: the scaled mean and the mean HSC mark. The scaled mean represents the average scaled mark achieved among the entire candidature of the subject, while the HSC mark mean represents the same for HSC mark. On this note, the Table A3 statistics are what’s used as inputs in ATAR calculators you will find around the web.

Now let’s look at some examples

**Example 1**

Suppose one student did Chemistry and another student did Senior science. If the Chemistry student scored in the 90th percentile in the 2010 HSC, their HSC mark would be 90 and his scaled marks would be 84.4. The Senior science student would need to achieve a HSC mark of 97 (estimate based on interpolation) and come close to being 1st in the state in order to earn the same number of scaled marks! (Remember, your ATAR is directly calculated off the total of your scaled marks across your 10 best units – it is scaled marks that gets you into the Uni course you want!)

Courses |
Number |
Type of Mark |
Mean |
SD |
Max Mark |
P99 |
P90 |
P75 |
P50 |
P25 |

General Mathematics | 30992 | HSC | 35.8 | 5.9 | 50.0 | 47.0 | 43.5 | 40.0 | 36.0 | 32.0 |

Scaled | 21.1 | 10.0 | 45.4 | 41.0 | 35.0 | 29.1 | 20.8 | 12.9 | ||

Mathematics Extension 2 | 3469 | HSC | 41.8 | 5.4 | 50.0 | 48.5 | 47.0 | 46.0 | 43.0 | 39.0 |

Scaled | 43.8 | 4.5 | 50.0 | 49.2 | 47.9 | 46.6 | 44.8 | 42.3 |

**Example 2**

Lets look at another set of contrasting subjects, to reinforce the point being made. Suppose one student does General Mathematics and another student does Maths Extension 2 (unfair comparison yes, but relevant in illustrating the point at hand). If the Maths Extension 2 student scored in the 90th percentile, their HSC mark would be 94 scaled mark would be 95.8. For the general mathematics student, even if he/she topped the state, only 90.8 scaled marks would be awarded.

Courses |
Number |
Type of Mark |
Mean |
SD |
Max Mark |
P99 |
P90 |
P75 |
P50 |
P25 |

Chemistry | 10330 | HSC | 37.4 | 6.5 | 49.0 | 47.0 | 45.0 | 42.0 | 38.0 | 34.0 |

Scaled | 31.7 | 9.2 | 50.0 | 45.9 | 42.2 | 38.8 | 33.5 | 26.1 | ||

Social Science | 4901 | HSC | 38.0 | 5.1 | 49.5 | 47.5 | 44.0 | 41.5 | 38.5 | 35.0 |

Scaled | 19.5 | 9.9 | 43.8 | 40.3 | 32.8 | 27.1 | 19.3 | 11.5 |

In 2010 there were 3469 Maths Extension 2 students, and 30,992 general maths students – almost ten times more students than Maths Extension 2! What the scaling system does is that you are rewarded less for coming first out of 30,992 students compared to coming in the 90th percentile among 3469 students (equal to around 347th).

**Conclusion**

While the results of these examples do sound amazing, it is acceptable from a statistical / technical analysis – the system rewards students who embark on more difficult subjects like Maths Extension 2 and Chemistry. From a technical standpoint, the system is ‘fair’. For those of you aiming for a ‘high ATAR’, this means you will need to score very high percentiles across all your lower scaling subjects in order to score a 99+ ATAR. This is difficult but not impossible and certainly not unheard of. As a general guide, for all your low scaling subjects (subjects with scaled means of 25 and below) you should aim to score a HSC mark of 95 or better, in order to not jeopardise your chances of achieving the magical 99+ ATAR.

A slight digression from topic: the significance of a 99 ATAR is the fact that Law and Medicine (though based on UMAT and interview results as well, the fact that median ATAR of UNSW and USYD medicine students are 99+ means ATAR is at least a significant indicator of chances of success in gaining admission to these courses)

Year 10 is a critical time for prospective HSC students. The reason is that the Preliminary subjects you choose in year 10 for year 11 will determine what subjects you ultimately do for the **HSC**. If you get your subject selection wrong, you may be stuck doing subjects you don’t particularly enjoy, or subjects that offer limited benefit in terms of scaling.

HSC scaling – a brief reintroduction

The subjects you choose in year 10 determine how much you will benefit from the process of scaling. Briefly, scaling refers to the process by which raw assessment marks (e.g. from your internal exams and external HSC exams) are converted into scaled marks, which are marks on a common scale that allows the degree of achievement in different subjects to be compared against one another in a statistically fair way. The scaling process is undertaken by the UAC and the result of this process – your aggregate scaled mark (out of 500) – is the sole determinant of your ATAR. Therefore we can safely say that **HSC scaling** is a big deal if you intend on scoring a high ATAR.

In order to maximise the positive effect of HSC scaling, one must choose courses that are ‘scaled high’ – or in technical terms, have a high scaled mean. The scaled mean for a subject is an important statistic, which tells us the average scaled mark obtained by the subject’s cohort. The higher this statistic for a subject, the higher the subject is scaled generally. Scaled means are publicly available in Table A3 published each year by the UAC.

For full technical details on how the scaling process works, see our article on the topic: http://www.duxcollege.com.au/hsc-scaling-i-49.html

So why is subject selection important

It’s important to get your subject selection right the first time, because there’s limited to no chance to change after you’re well into year 11. Also the beneficial effect of scaling could be huge, or could be non-existent, depending on which subjects you chose. If your goal is to maximise your ATAR, you should also consider the scaling of a subject on top of whether you think you’ll enjoy it. The general rule is to select subjects you’ll be good at, amongst the subjects that offer a scaled mean of 29/50 or above.

What are some good subjects?

Have you noticed a pattern with graduates that score an ATAR of 99+? A significant portion of them do a combination of the following subjects:

- English Advanced
- Maths Extension 1
- Maths Extension 2
- Physics
- Chemistry
- Biology
- Economics
- Modern history
- History Extension
- English Extension 1
- English Extension 2

What these subjects all have in common is that their scaled mean is all above 28/50 (most are around 30, with the best scaling from Maths Ext1 and Ext2 which goes as high as 45/50).

These subjects have higher scaled means due to the way in which the scaling process works. Year after year, the candidature of these subjects does comparatively better than their peers who do other subjects, including compulsory 2 units of English, which is used as a common scale to compare. What this means is that a high scaled mean often indicates higher subject difficulty, due to the fact that those students who do high-scaling subjects tend to do comparatively better than their peers in other subjects.

However, when it comes to advising students on what subjects to choose for year 11, we always advise students to go for as many of the aforementioned subjects as possible – so long as they can handle them. For example, a student with aptitude and interest in maths should always choose Maths Ext 1 in year 11 – this opens the possibility to take up Extension 2 in year 12, which has a massively positive scaling effect (the majority of ATAR 99+ graduates have completed the Extension 2 course). If a student absolutely hates maths, that’s OK – choose some sciences and some humanities subjects (e.g. English Extension 1 and Modern History with History Extension, or Economics). Many graduates with a combination of humanities and social sciences have scored 99+ without having done any level of maths! What’s important is the ability to understand your own strengths and weaknesses, and choosing decently-scaled subjects based on this understanding.