How do ATAR estimates be accurate considering HSC externals are left that weigh up to 50% of your HSC mark. Most of these estimates I seen so far have been only one or two off the persons actual atar. Considering a student gets like a 60 estimate but aces the externals with their cohort then shouldn't the final atar be much higher? Does the BOS be consider factors on how hard a schools internal exams are, as well as the harder marking by the school compared to the externals?