How Do I Aggregate Grades for a Category or for the Course Grade?

Valid for Moodle 2.5.  Updated on 10/23/2013.Moodle supports the a variety methods for aggregating the grades in a category to determine a grade for the entire category. The course grade is the grade for the category that includes everything in the course.

Most of images below are from a user report. The first column is the number of points the student received, the second column is the number of points possible and the third is the student's percentage.

  • Mean of grades - based on percentage score for each item. For example if a student gets 100 on a test worth 100 points and 2 on a 4 point quiz, the final grade would be (100% + 50%)/2  = 75%.
    Mean of grades listing

  • Weighted mean of grades - Different items are assigned arbitrary weights.  For example, if a student gets 100 on a test worth 100 points and a weight of .4 and 2 on a 4 point quiz with a weight of .5, the final grade would be (100% * .4) + (50% * .5) = (40% + 25%) = 65% and  65%*(1/.9) = 72.22%.  The final calculation corrects for the fact that the weights given don't add up to 1.
    weighted mean of grades display

  • Simple Weighted mean of grades - Weights given to each item are based on the total number of points for that item.  This makes high point items even more important that with a simple mean calculation. Note that it is possible to add extra credit to this calculation.  For example, if a student gets 100 on a test worth 100 points and 2 on a test worth 4, his grade would be (100 + 2)/(100+4) = 98.08%.
    Simple weight of grades

  • Mean of grades (with extra credit) - With this method at least one item is designated as the extra credit item. This is done by designating a multiplier value for the item in the gradebook view. A multiplier of 0 means the item is not extra credit. 
    Extra credit from simple view

    The total for the category is calculated by adding up all the individual results, including extra credit, and then dividing by the number of non-extra credit items.
    For instance, a student gets 75 points out of 100 on the first test and 1 out of 4 on the second.  However, they also got 2 out of 10 on the extra credit with a multiplier of 2 for 20% x 2 for 40% extra credit. The final score for the category would be (75 + 25 + 40)/2 = 70%. The total can not be greater than 100%. Note in the illustration below, the table does not reflect the multiplier in the extra credit row but does include it in the final calculation.
    Extra credit display

  • Median of grades - The grade is the numeric middle grade. So if the student had grades of 100%, 75%, 20% the median grade is 75%.
    Median display

  • Highest grade - Using the grades from the Median example, this weight would yield 100%.
  • Mode of grades - The grade that occurs most often is used.  If we had grades of 100, 75,  20, 20 and 10 the final would be 20%.
    Mode display

  • Sum of grades - The grade is calculated based on the total number of points received divided by the total number of point possible.  This method that doesn't convert individual items to percentages before aggregation.  For example if a student gets 100 on a test worth 100 points and 2 on a 4 point quiz, the final grade would be 102/104 = 98.08%. Note that it is possible to add extra credit to this calculation. It works like Mean of Grades (with Extra Credit) except there is no multiplier and you simply check a box to indicate with items are extra credit.
    Sum of grades

Moodle.org has a page of grade aggregation.