What is an R. Count in the item analysis?

What is an R. Count in the item analysis?

لە لایەن Patrick Malley -
Number of replies: 5
I know what the function of an R. Count is - to count the total number of students who guess a particular answer.  But, what is "R"? 

This is probably something simple or statistical that I am missing?  Is it ratio?
تێکرایى نمرەپێدراوەکان: -
In reply to Patrick Malley

Re: What is an R. Count in the item analysis?

لە لایەن Joseph Rézeau -
وێنەی Core developers وێنەی Particularly helpful Moodlers وێنەی Plugin developers وێنەی Testers وێنەی Translators
Maybe simply R = Right (i.e. total number of students who guessed the answer correctly) ?
In reply to Joseph Rézeau

Re: What is an R. Count in the item analysis?

لە لایەن Tim Hunt -
وێنەی Core developers وێنەی Documentation writers وێنەی Particularly helpful Moodlers وێنەی Peer reviewers وێنەی Plugin developers
I have not worked this out yet. Looking at the quiz reports is pencilled into my personal roadmap for between October and December.

It may be some sort of regression co-efficient. Other quiz analysis systems use a statistic that is basically "is there a good correlation between the students' score on this question, and their score on the whole quiz?" If there is a good correlation, then that question is probably a good indicator of ability.

By the way, have you tried clickin on the help buttons or looking in MoodleDocs?
In reply to Tim Hunt

Re: What is an R. Count in the item analysis?

لە لایەن Maria B. -
Good indicator of reliability is "image" - squared multiple correlations between each variable and all other variables.

Discrimination Coefficient means Corrected Item-Total Correlation or not?

DC = Sum(xy)/ (N * sx * sy)

Some statistical packages, like SPSS, use overall quiz scores decremented by score for that particular queastion i.e. C = Y - X



In reply to Maria B.

Re: What is an R. Count in the item analysis?

لە لایەن Timothy Takemoto -

I don't think it is corrected. It does not mention that in the documentation.

When all the students get a question correct, and so I guess that the discrimination coefficient should be 0 (zero) because it has no power of discrimination but it is also not reverse discriminating, but in moodle 1.53 it is calculated to be 999.

Tim

In reply to Patrick Malley

Re: What is an R. Count in the item analysis?

لە لایەن Patrick Malley -
I'll reply to myself with a possible answer here.

Someone in a training session I was conducting at my school said "Raw."

Whether this is correct or not, I'm not sure. But, it works. "Raw Count." "Raw %."

Thought I should share.