Part 2: Scaling of HSC Marks

What is scaling?

The scaling of HSC marks is the process of ‘standardising’ raw marks (remember, your HSC Mark is the average of HSC exam mark and moderated school assessment mark) provided by NESA and then estimating what these marks would have been if all courses had been studied by all students.

At the end of this scaling process, different marks in different subjects are converted to a single UAC score (also known as an ‘aggregate’) for every subject. Although scaled marks generally differ from the raw marks from which they are derived, the ranking of students within a course is not changed.

Scaling is like converting a foreign currency to Australian currency.

You can compare scaling to a conversion of foreign currency (HSC Mark of a subject) to Australian currency (scaled mark of a subject). As different exchange rates apply to different currencies, so are different conversion rates applied to HSC marks of different subjects when they are converted to scaled marks for comparison.

Why scaling is necessary

How do you compare one student who scored a 90 in Mathematics Extension 2 to another student who scored 90 in Mathematics Advanced? It is impossible to do such a comparison without applying scaling to the marks!

For example, the table below shows HSC marks in Maths Ext 2 and Maths ADV can only be compared fairly using scaled marks.

Since each student undertakes a different combination of subjects, their performance in one subject will not necessarily reflect their ability in different subjects.

The same marks in different courses are not necessarily equal: just as different currencies are compared using the exchange rate, scaling is used to compare marks from different courses.

Scaling allows a comparison of marks from ‘difficult’ and ‘easy’ subjects. The underlying principle of scaling is that a student should neither be advantaged nor disadvantaged by choosing one HSC course over another.

Scaling graphs of HSC subjects

The scaling graphs of the following HSC subjects are provided below:

1. English courses
2. Mathematics courses
3. Science courses
4. Humanities courses
5. Language courses

The scaling graph depicts a relationship between Scaled Mark vs Percentile rank. The vertical axis represents the scaled mark, which is a UAC score converted from an HSC mark. The horizontal axis represents Percentiles, which is a student’s rank in the course.

You can use the Matrix ATAR calculator to determine your HSC Mark, Percentile and Scaled marks for each course as well.

English courses

Scaling Graph for English

The scaling graph for English courses is shown below.

From the English Scaling graph, we can see:

• A student ranked in the 90th percentile will receive a scaled mark for:
  1. English ESL: 37.5/50 or 75/100
  2. English Standard: 27.6/50 or 55/100
  3. English Advanced: 42.5/50 or 85/100
  4. English Extension 1: 43/50
  5. English Extension 2:  44/50
• A student ranked in the 70th percentile (top 30%) in English Advanced will receive the same scaled mark as the student ranked in the 99th percentile (top 1%) in English Standard.

Insights from English scaling graph

If you are capable of undertaking Advanced English as one of your ATAR courses, then you should avoid undertaking Standard English as it is not a subject that is scaled well.

If you are good at English, consider Advanced or Extension English

English is the only compulsory subject and therefore your best two units of English are taken into account when determining your ATAR. Therefore English plays an important role in determining whether you get a good ATAR or an exceptional ATAR.

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Mathematics courses

Scaling Graph for Mathematics

The scaling graph for Mathematics courses is shown below.

From the Mathematics Scaling graph, we can see:

• A student ranked in the 90th percentile will receive a scaled mark for:
  1. General Mathematics: 35/50 or 70/100
  2. Mathematics Advanced: 42/50 or 84/100
  3. Mathematics Extension 1: 47/50 or 94/100
  4. Mathematics Extension 2: 48/50 or 98/100
• A student ranked in the 70th percentile (top 30%) in Mathematics Extension 1 will receive the same scaled mark as the student ranked in the 99.9th percentile (top 0.1%) in General Mathematics.

Insights from Mathematics scaling graph

If you are a capable Mathematics student and are deciding between Extension 1 & Extension 2 Mathematics, you should still undertake Extension 2 Mathematics.

If you are good at Mathematics, consider Mathematics Ext 1 or Ext 2.

Mathematics Extension 1 & 2 is scaled very well. A Mathematics Extension 1 & 2 student will need to be ranked in the 76th percentile (top 24%) and 52nd percentile (top 48% ) to receive a scaled mark of 45/50 or 90/100 whereas or Mathematics Advanced student will need be ranked in the 98th percentile (top 2%) to receive the same scaled mark.

If you choose General Mathematics, you must ace it.

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Science courses

Scaling Graphs for Science

The scaling graph for Science courses is shown below.

From the Science Scaling graph, we can see:

• A student ranked in the 90th percentile will receive a scaled mark for:
  1. Biology: 39/50 or 78/100
  2. Chemistry: 41/50 or 82/100
  3. Physics: 40/50 or 80/100
  4. Senior Science: 33/50 or 66/100
• A student ranked in the 70th percentile (top 30%) in Chemistry will receive the same scaled mark as the student ranked in the 97th percentile (top 3%) in Senior Science.

Insights from Science scaling graph

Chemistry and Physics scale slightly better than Biology.

If you are good at Science, consider Chemistry and Physics or Biology over Senior Science.

Therefore, Biology students must be ranked higher to obtain the same scaled mark as Physics and Chemistry students.

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Humanities courses

Scaling Graphs for Humanities

The scaling graphs for Humanities courses are shown below.

Insights from humanities scaling graphs

Economics scales better than business studies or legal studies. An Economics student only needs to be ranked in the 80th percentile to receive 40/50 scaled mark whereas a Business Studies student will need to be ranked in the 95th percentile to receive 40/50.

Modern History scales better than Ancient History. Extension subjects such as History Extension always scale well.

If you do are good at Music, consider Music 2 or even Music Extension over Music 1.

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Language courses

Scaling Graphs for Languages

The scaling graphs for Language courses are shown below.

Insights from language scaling graphs

Continuers scale better than beginner courses. For example, Japanese Continuers scales better than Japanese Beginners.

If you are good at Languages, consider Continuers course over the Beginners course.

Latin Continuers and Latin Extension are the best scaling courses for Languages.

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Choosing the right HSC subjects

When choosing your subjects for Year 11 and 12, students should not choose their subjects based on scaling. However, scaling should be used to determine the percentile required to achieve your desired scaled mark for each course.

Students are advised to consider the following questions when selecting subjects for Year 11 & 12.

1. Do I find the subject interesting and/or do I like the subject? For example, do I find science subjects more interesting than humanities subjects?
2. Do I understand clearly what the subject involves? For example, junior science is very different to Chemistry, Physics and Biology.
3. Is the subject a prerequisite or recommended for the university course that I hope to undertake in the future? For example, if I want to undertake a Medical course at University, then should I consider studying both Chemistry and Biology?
4. Do I understand the scaling of the subject? Subject selection should not depend on the scaling of each subject alone. No matter how well a subject is scaled, if you do not perform well in the subject then scaling does not help.