The ATAR explained

UAC compares the difference between HSC marks and the ATAR to a running race: the HSC mark is your time, which is not compared with anyone else's, and the ATAR is your place in the field. That analogy is worth remembering, because it explains why a student's marks and rank can tell different stories.

The average sitting near 70.00 rather than 50.00 surprises many families. UAC explains it: if every school student received an ATAR the average would be 50.00, but some students leave school early, and those who stay on to receive an ATAR are a smaller, more academically able group.

UAC also notes that NSW and ACT ATARs are equivalent to those in other states, so an ATAR of 85.00 in NSW means the same as 85.00 elsewhere. The rank is national in meaning, even though each state calculates its own.

Universities usually admit on a selection rank, which UAC describes as the ATAR plus any applicable adjustments, and many consider other things, such as a portfolio, an interview or a test. For computing courses that can make a portfolio of real projects genuinely useful, but that is a university's call, not ours.

English goes in first, even though its invented value of 30 is the lowest on the list. Then the remaining courses are sorted from highest to lowest value, and courses are taken until 8 more units are filled: Mathematics Advanced, Physics, Software Engineering and Modern History. Business Studies misses out.

Adding up the invented values gives 2 times 30, plus 2 times (40 + 39 + 38 + 35), which is 60 plus 304, or 364 invented points. The number means nothing in the real world. The point is the shape of the rule: one compulsory block, then the highest of the rest.

This is a nice small programming exercise in its own right: sort a list, honour a constraint, stop at a limit. Students who code can write it in a few lines of Python and then add UAC's other rule, the cap of 4 units on calculus-based mathematics, to see how a constraint changes a selection.

What the illustration cannot do is tell a student their ATAR. Real scaled marks depend on everyone else's results in every course that year, which is why we never offer predictions, and why families should be wary of anyone who does.