I am using exams2moodle, I would like to implement a custom evaluation policy for multiple choice questions, based on the number of discrepancies between the correct answers and the answers given by the student. In all multiple choice questions, there are 5 answer options.
If there are no mismatches, the student will have 1 point. If there is only one mismatch (the student selected one wrong answer, or did not select one correct answer), the student will have 0.5 point. If there are two discrepancies, the student will have 0.2 point. If there are three or more discrepancies, the student will have 0 point.
Is it possible to use the exams2moodle and exam_eval functions to implement this specific method? Or is it impossible using the moodle notation system?
Thank you very much for you help.
TL;DR: It is not possible to implement this method in Moodle.
What Moodle does: In general Moodle can only assign points to checked boxes. Typically, these are positive if a correct item was checked and negative if an incorrect item was checked. In contrast, unchecked boxes always yield no points. Our exams_eval() essentially follows the Moodle approach.
Details: Evaluate exam in moodle with a custom evaluation scheme