Moodle exam with minimum zero points for multiple choice task

How can I create a moodle question via the {exams} package that scores multiple choice questions with at least zero points?

I already tried:

exams2moodle(..., mchoice = list(eval = list(negative = FALSE)))

If I understand your question correctly then the default setting in exams_eval() and hence also in exams2moodle() does what you look for:

• partial = TRUE, i.e., there are partial credits for each correct list item that is checked.
• rule = "false2", i.e., there are negative partial credicts for each incorrect list item that is checked.
• negative = FALSE, i.e., the sum of points within the exercise cannot become negative.

As an illustration I generated exams2moodle("switzerland", points = 5) which generates an exercise where the first two list items are correct (yielding 5/2 positive points each) and the other three list items are incorrect (yielding 5/3 negative points each).

With 1 correct and 1 incorrect item you get 0.83 points = 5/2 - 5/3.

The point some of 1 correct and 2 incorrect items would be -0.83 points = 5/2 - 2 * 5/3; but it is constrained to be zero:

And a last variation to show how this works: 2 correct and 2 incorrect yielding 1.67 points = 2 * 5/2 - 2 * 5/3.