1. Your lecturers determine a raw mark by aggregating the results of your assessment tasks. (In Philosophy 2001, I was ranked =16/37 with a raw mark of 83.25. Max: 90.5, Median: 82.25, Min: 74.25, Mean: 82.6, StDev: 4.1)
2. Upon the conclusion of the course, the lecturers from all three Distinction Courses hold a joint meeting to determine the maximum mark and the raw grade cut-offs for each course. This process places the marks from all three courses on the same scale, resulting in a set of adjusted marks. (Informal enquiries have indicated that the maximum adjusted mark for Philosophy is usually set to be around 95 - speak to Adrian for details. My raw mark of 83.25 became an adjusted mark of 87.)
3. These adjusted marks are sent to the Board, and undergo a further transformation to become total weighted marks. I don't have any details of this transformation, though I suspect that it simply sets the maximum mark in each course to be 100. (My adjusted mark of 87 became a total weighted mark of 88.) This total weighted mark indicates your final grade for the course - e.g. a total weighted mark of 85+ will result in the words "High Distinction" appearing where your examination mark would normally appear.
4. The total weighted marks from the three Distinction Courses are combined under a single "Distinction Course" label, and thus the scaling algorithm treats them as though they were from a single course.
5. The scaled marks are separated into the three courses again for the purposes of statistical reporting.
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A form of multi-linear mapping is used in the third step to transform raw marks to adjusted marks using the raw grade cut-offs (in the same way that the Board performs its aligning process). If it is decided that the maximum raw mark of 90.5 is to become a maximum adjusted mark of 95, and that a mark of 82 should be the raw grade cut-off for a High Distinction (85), then a simple linear transformation is used to map raw marks between those points to the corresponding adjusted marks.
It is the equivalent of determining the equation of a straight line through the points (90.5, 95) and (82, 85) and then pushing all other raw marks in the range [82, 90.5] through that equation.