Partial Credit for Multiple Answer Questions

[ebealle]

If I understand how partial credit is calculated then I am confused. If I have a Multiple Answer Question that has two correct answers. If a student chooses one correct answer and one incorrect answer then they essentially cancel out and the student gets no points instead of the points he/she should get. 

So the question is worth 20 pts. There are 4 choices. 2 are correct and 2 are incorrect. So a student chose one correct question and one incorrect question. He received 10 pts for the correct choice and -10 pts for the incorrect answer, resulting in a 0 pts. In my head, he should have received 10 pts.

Am I missing something?

[stimme]

@ebealle The instructor guide How do I create a Multiple Answer question in New Quizzes? layouts out the way partial credit is calculated if the option "partial credit with penalty" is selected. (The other choice is all or nothing exact match, which is pretty clear.) The reason "partial credit without penalty" is not an option is that it would let students select all answers and get full credit every time; it would let students game the system.

There's a feature idea conversation (Partial Credit for Multiple Answers WITHOUT Penalty)where some commenters are asking for the partial credit without penalty calculation. But the original poster and some commenters are expressing a need for no penalty at the same time as constraining how many possible answers a student may select. That idea could be considered a distinct question type, and one commenter called it "multi select".

[leward]

Here's another way to think about it.  If students aren't penalized for wrong answers, then they could simply select all possible answers and get the question correct.  The penalty discourages students from guessing.  For you example, students will get partial credit if they only choose one of the two correct answers.