Moodle Teacher Guide: Aggregation Types

Mean of grades

Weighted mean of grades

Simple weighted mean of grades

Median of grades

Natural

Extra Credit

Mean of grades: The sum of all (normalized) grades ÷ the total number of grades

When to use Mean of grades: This aggregation type averages all the grades in a category where each item is given equal weight. For instance, a quiz worth 20 points is worth the same amount as a quiz worth 10 points.  It is best to use this type of aggregation when all individual grade items in a category have the same amount of maximum possible points, such as all quizzes have a possible maximum value of 10.

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Weighted mean of grades: Each grade item is multiplied by a weight assigned by the instructor. The assigned weight tells Moodle how much that particular grade counts toward the final grade calculation.  For instance, an assignment given a weight of 2 counts twice as much toward the final grade as an assignment given a weight of 1. An assignment given a weight of 75 counts three times as much as an assignment given a weight of 25.

When to use Weighted mean of grades: Use this aggregation type when you want each category or grade item to be weighted differently toward the final grade calculation.

Example 1: Calculating weighted grades within a category (using Categories and items > Simple view)

• Calculation:

[(0.8 x 2.0) + (0.9 x 1.0) + (0.95 x 2.0) + (0.9 x 3.0)] / 8.0 = 0.8875

Category grade for the student:  0.8875 x 100 = 88.75

• In the above example, notice the Category total does not have to equal the sum of the total maximum points for all assignments.  Additionally, the assigned weights do not have to add up to 100 for this calculation to work. 

Example 2: Calculating weighted categories within a gradebook

From Syllabus:

• Attendance = 5%
• Assignments = 30%
• Forum Participation = 20%
• Quizzes = 45%

Categories and items view from Gradebook:

• Select Weighted mean of grades from the course's Aggegration column at the top of the screen
• Enter the weighted value for each category in the Weight column

• Calculation:

[(1.0 x 5.0) + (0.9 x 30.0) + (0.95 + 20.0) + (0.85 x 45.0)] / 100 = 0.8925

Category grade for the student: 0.8925 x 100 = 89.25

• The weights in the above example add up to 100 in order to simplify the assignment of percentages.  It is recommended, but not necessary for them to total 100.

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Simple weight mean of grades: This aggregration type is the same as weighted mean of grade, except that a grade item's maximum point value determines how much it weighs toward the final grade calculation.  

When to use Simple weighted mean of grades: It is best to use this type of aggregation when you have items graded on differing scales and you want the items to contribute to the final grade based on their possible maximum points.  For instance, an assignment worth a possible100 points will count five times more toward the final grade calculation than an assignment worth a possible 20 points.

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Median: This aggregation type takes the middle grade or mean of two middle grades when grades are arranged in order of size. Median prevents outliers from skewing the results.

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Natural: By default, Natural weighting produces a Sum of the Grades. The sum of all grades earned are divided by the total possible points. However, Moodle now provides a way to custom weight each assignment.

Without weights:

When to use Natural:

• When you want to generate a student's total points earned out of the total maximum points possible
• To factor in an extra credit grade

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Grade items can act as extra credit with some aggregation types.  In general, extra credit points add to the earned points but not the maximum possible points.  Moodle will not report grades greater than the maximum possible points even if the addition of extra credit points calculates over the amount.

Configure extra credit

• Grades > Categories and items > Simple view
• Add a check mark in the box under the Extra credit column
• Click Save changes at the bottom of the screen

Note: If a grade item is created in the gradebook (versus through a Moodle module like assignment, quiz, etc.) the Extra Credit option will not appear until the grade item is saved, return to the gradebook settings and edit the grade item.

Aggregation types that can be configured with extra credit items:

Simple weighted mean with Extra Credit

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