We are trying to interrogate time on task for quizzes and are having trouble making sense of some of the data.
In the quiz_submission_fact and quiz_submission_historical_fact there is a time_taken field that often has large numbers, equating to days. It looks like the student is going into a quiz that allows multiple submissions having already completed an attempt and then leaves again meaning that their incomplete 'attempt' is submitted on the due date. As this is the latest 'submission' it is marked as current and the time_taken seems to be calculated as being from the first entry into the quiz to the due date. This is skewing the average time in the quiz statistics view for instructors where a result of 15 minutes would be expected, but 8 hours is recorded instead, for example. Also, previous attempts don't seem to have any time stats recorded in the historical files.
Has anyone found a reliable way to search through this data (other than using less than some arbitrary number)? Is this part of the road map for the quiz tool rewrite?