Grading multiple choice and cloze questions created with exams2moodle()

Question

I am using exams2moodle() from R/exams to create multiple choice and cloze questions in Moodle. Before preparing exams, I would like to be certain how Moodle comput

Answer 1

Overview

Essentially you are correct. However, I will discuss a few details below that are Moodle-specific because Moodle does not support the full flexibility of the exams_eval() strategies from R/exams.

(Note: Some of this functionality, notably for cloze questions, has been improved in R/exams 2.4-0 which at the time of writing is the development version and not yet on CRAN. Until it is, you can get it with install.packages("exams", repos = "http://R-Forge.R-project.org"))

Multiple-choice (mchoice) questions

• Moodle only supports evaluations with partial credits and thus setting partial = FALSE is not possible.
• The evaluations in Moodle are always such that not ticking a box yields zero points. Only ticking a box can yield points (positive or negative).
• Ticking a correct box always gives the proportion 1/#ncorrect of the overall number of points were #ncorrect is the number of correct answer alternatives.
• Ticking an incorrect box can give a negative amount of points. The precise amount is controlled by the rule specification. For rule = "false" an incorrectly ticked box gives the proportion -1/#incorrect = -1/(n - #ncorrect).
• As this is pretty harsh in the case of exactly one incorrect alternative (ticking it erases all points), there is rule = "false2" which is the default. An incorrectly ticked box still subtracts the proportion 1/#incorrect except in the case where #incorrect = 1 when 1/2 is subtracted.
• The overall amount of points from all boxes combined cannot become negative! It may be displayed as negative in some situations but is actually treated as 0. Thus, the R/exams argument negative = TRUE would be ignored, it is implicitly always negative = FALSE.
• Because only ticking correct answer alternatives can yield positive points, there needs to be at least one correct answer alternative. If a multiple-choice question without correct answer alternatives is used, it always yields zero points.

Single-choice (schoice) questions

• Essentially, the same rules as above apply. The main difference is that Moodle uses radio buttons (rather than check boxes) for single-choice questions. Thus, participants can only select one alternative and not several ones.
• The other important difference is that the sum of points can become negative! (Unlike for multiple-choice questions.)
• exams2moodle() currently uses the same default evaluation strategy rule = "false2" for single-choice questions. This assures that the expected number of points from random guessing strategies is zero. (However, we are thinking about changing the default to rule = "none" which seems to be more commonly used, i.e, selected an incorrect alternative just gives zero points.)

Cloze questions

• The different parts of a cloze questions are evaluated separately and then simply summed up.
• For schoice or mchoice items within a cloze question, the same rules as above apply. Thus, points can become negative for single-choice questions but not for multiple-choice questions. The default is, however, not to use negative points.
• Note also that mchoice items within a cloze are currently not supported very well by R/exams because they were not supported at all by Moodle until recently. See Cloze question combining mchoice and num import in Moodle We hope to improve this in future versions.
• By default the overall number of points is split equally among the items within a cloze. However, expoints can be set to a vector of the same length as the number of items giving the number of points for each. (This was improved in the current development version 2.4-0 on R-Forge, though.)

Marks

The assignment of marks to the points achieved cannot be controlled from exams2moodle() in R/exams. Thus, you have to configure this in Moodle when putting together the quiz there.