The professor teaching a large introductory class gives a fi

The professor teaching a large introductory class gives a final exam that has alternate forms, A, B, and C. A student taking the exam using Form B is upset because she claims that Form B is much harder than Forms A and C. Discuss how percentile point data might be useful to determine if the student is correct.

Solution

If the data is in percentile point format, then we can get the cutoff marks of different percentile. For example, if the 90 percentile score of form A and C are 450 and 435 respectively, and the 90 percentile score of the form B is less than 400 (say 390), then we can conclude that the form B was harder than A and C. The converse is also true. That is, if the percentile scores are not different from each other then the papers are not different from each other.