Therefore, you need some way of seeing their quiz attempts, so you can delete them manually if you want to.
However, exactly which quiz attempts should be displayed for each option in the quiz report is something I have never entirely got my head round.
A real bug in this module I think is that when you reset a course with quiz in it (in preparation for a new class), the quiz attempts records are not erased. And when you enrol a completely new class of students, these remnant will mess up the quiz report, and it's not possible to delete them as the "owners" (the old batch of students) have all been cleared from the course.
Have I missed anything when resetting courses?
I worked around this by adding 2 fucntions to mod/quiz/lib.php: quiz_delete_userdata and quiz_reset_course_form (copied and modified from lib file of forum module)
Not sure if this is the correct way, but it works for me : )
I like having the "old" students data in the quiz report as it provides a larger amount of data for my quiz questions when analyzing the question stats but it would be nice to isolate the quiz reports/stats to current students and all students when you view it.
yes, would be really nice if data can be separated that way.