In my course, I have a certain number of students who withdrew from the course a few weeks ago. However, since the list of students is fed by an LDAP database (which is not properly maintained), these students are still listed in the list of course participants.
How do I ensure that the partial scores (all of them wrote the first mid term exam, but nothing after the second mid term) corresponding to these students are ignored in average and standard deviation calculations (I am trying to figure out how to use z-scores in Moodle)?