How the VCE ATAR is calculated

For each Unit 3 and 4 study, the VCAA combines your school-assessed coursework or tasks with the external exam to produce a study score from 0 to 50. Study scores are standardised so that in a study of reasonable size the mean is about 30 and the standard deviation about 7. A 40 places you around the top 9% of that study's cohort; a 30 is the middle.

The VCAA statistically moderates school-assessed marks against the exam so that a 40 at one school means the same as a 40 at another.

A study score compares you with the students who took that study. To compare across studies, VTAC scales each study score using how those same students performed in all their other studies. If a study's students tend to score highly elsewhere, its scores scale up; if not, they scale down. Scaling is recalculated every year and published as a table of raw study score against scaled score for every study.

Scaled scores can go above 50 for the strongest studies and well below the raw score for others. A scaled score is not a judgement of difficulty; it is an adjustment for the cohort.

VTAC adds up your scaled scores in a fixed pattern:

• Your best scaled score from the English group (English, English Language, Literature, or English as an Additional Language).
• Your next three best scaled scores. Together with English these are the "primary four".
• 10% of your fifth scaled score, and 10% of your sixth, if you have them. These are the increments.

Grouping rules limit what can sit in the primary four: at most two Mathematics studies, at most two from the English group, and similar caps for languages and some other groups. A completed but unscored VET program can contribute a block credit increment worth 10% of your fourth (lowest primary-four) score.

The aggregate is ranked against the Victorian age cohort to give the ATAR, from 99.95 down to 30.00 in 0.05 steps. Anything lower is reported as "less than 30".

A student finishes with study scores of English 36, Mathematical Methods 34, Chemistry 33, Psychology 40, Business Management 38 and Physical Education 35.

1. Each study score is scaled using that year's VTAC table. Suppose they become English 37, Methods 40, Chemistry 38, Psychology 39, Business Management 36 and PE 33.
2. English (37) is the compulsory first score.
3. The next three best are Methods 40, Psychology 39 and Chemistry 38. Primary four = 37 + 40 + 39 + 38 = 154.
4. Increments: 10% of Business Management (3.6) and 10% of PE (3.3).
5. Aggregate = 154 + 3.6 + 3.3 = 160.9.
6. VTAC ranks that aggregate against the cohort. In recent years an aggregate near 160 has corresponded to an ATAR in the high 80s.

• The primary four carry ten times the weight of the increments. A one-point rise in a primary-four study is worth ten times a one-point rise in your fifth.
• English always counts, whether or not it is your strongest study.
• Study scores are about rank within the study, so the exam is where you can still move relative to everyone else late in the year.