Published calibration evidence
A mark you can test.
Students test essay-marking tools the obvious way: submit the same essay twice and see if the number holds. We think that's exactly right — so we run that test against a frozen benchmark and publish the results, stamped with the date and engine version they were measured on. To our knowledge, no other GAMSAT marking service publishes any calibration evidence at all.
These numbers describe an older version of our marking engine.
They were measured on engine je-2026-08a; we are now running je-2026-09b. The figures below are real and unedited, but until we re-run the benchmark on the current engine they are evidence about the older one. We would rather say that here than let you assume otherwise.
±0
Re-mark consistency
Repeat-marked probe essays land within 2 points of themselves (median 0) in our frozen-benchmark runs. Measured 2 August 2026, engine je-2026-08a.
6 pts
Raw gap between the Judges
Average raw gap between our two independent AI Judges' marks on the same essay, before they are reconciled into one mark, across the benchmark. Every mark is this cross-check; a real disagreement calls in a third reading to settle the split. Measured 2 August 2026, engine je-2026-08a.
47/48
In expected range
Essays landing inside their expected score range on the frozen benchmark — a consistency check against the engine's own reviewed baseline, not against official ACER scores. Measured 2 August 2026, engine je-2026-08a.
The method, plainly
ACER publishes exactly two assessment criteria for Section II — the quality of the thinking, and the control of language in expressing it — and no marking rubric. Our instrument is six sub-criteria built from those two published criteria, with what each level on our reported scale means fixed by written reference essays the Judges are shown — not by any real ACER result, because ACER releases none — and watched by regression evals: a frozen benchmark of 48 essays with expected score ranges, run on a drift schedule and re-run deliberately around engine changes. When we deliberately change marking behaviour, the benchmark is re-frozen in a recorded commit so score movement always comes with a recorded reason. When a change has shipped ahead of its re-run — as one has now — this page carries a notice at the top saying so, because a statistic that does not name the engine it was measured on is a claim about a configuration that may no longer exist.
Every essay, on every plan, is marked by two independent AI Judges and cross-checked; ACER itself states that Section II responses are “scored independently three times” — the same principle. When our two Judges genuinely disagree, a third AI reading from a different model family settles the split: each criterion is decided by the middle mark, disclosed on the grade.
Honest limits: these are calibrated practice estimates, not official ACER marks — only ACER issues those, on exam day. Consistency is measured on our frozen benchmark, not on your individual essay. GAMSAT® is a registered trademark of ACER, which is not affiliated with and does not endorse Aptavia.
Looking for Sections I and III?
Those are multiple-choice, so they are measured rather than marked: question difficulty from real attempts, papers equated against our own bank, and an error band published with the score.
How our practice questions are measured