"Multiple Answer" Quiz Question Option - Canvas grading method inconsistent

[hhouseman]

A student brought to my attention that the #MultipleAnswer #Quiz question I offered was graded by Canvas strangely.  And he was correct!  I looked at all of my students responses for that question and there was no clear pattern, in other words, I have no idea how Canvas calculates their scores for these questions.  If the question was worth 2 points, and there were 5 correct answers that the student needed to mark, it should be a straightforward .4 points per option, but it's not like that.  I had to award some points back, and unfortunately, had to take some points away from some students ... it's not graded consistently by canvas at all.  Is there an explanation, or a plan to fix this feature?  I really like this question option and want to be able to trust Canvas's grading!

[Steve_Watts]

Hi  @hhouseman 
I'm not sure if you're talking about the new quizzes tool or legacy quizzes, but with legacy quizzes I believe there is an algorithm that Canvas uses to calculate the score for the question. As well as giving marks for each of the correct answers that the student selects, marks are deducted if they select an incorrect answer. If there was no penalty for selecting incorrect answers, a student could select all of the possible answers to be sure that they had all of the correct ones.
For example: a question is worth 5 points and shows 10 possible answers where 5 of them are correct. The student needs to select the 5 correct answers and none of the incorrect ones to get full marks. If they select 6 answers - the 5 correct ones and an incorrect one - a point is deducted for the incorrect selection so the student scores 4 marks for the question.
Does the way your questions have been graded seem to fit this pattern?