My icculus.org/quake3 patches got commited!
Changelog
The X-axis represents the actual knowledge level of a hypothetical student, so a 700 promille on the X-axis of the graph means the student factually knows the answer to 700 promille of all statements and has to guess the remaining statements. The Y-axis represents the actual grade that would have been assigned to the student in question. Taking a look at the above graph the purple graph represents an ideal world without guessing, the blue graph represents the two statement multiple choice examination style, and it shows a delta of up to 250 promille below ideal grading. So this style of questioning is hardly fair at all.