Grade aggregation types

Moodle offers a number of ways to calculate the gradebook. Aggregation methods can also be mixed within the gradebook. For example, one category can use a mean of grades while the overall gradebook is set to weighted mean of grades. If you need help setting this up, please contact John, Laurie, or Anne at the phone numbers/emails in the right hand sidebar.

Mean of grades – The sum of all grades divided by the total number of grades

Weighted mean of grades – Each grade item is multiplied by a weight assigned by the instructor.

Simple weighted mean of grades – This aggregation 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.

Median of grades – The middle grade when all grades are arranged in order of size

Natural – The sum if all grade values scaled by weight

 

Mean of grades

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

A1 = 70/100, A2=20/80, A3=10/10, category maximum grade = 100
(0.7 + .25 + 1.0)/3 = 0.65, category grade = 0.625 x 100=62.5

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.

 

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.

A1=70/100 weight 10, A2=20/80 weight 5, A3=10/10 weight 3, category maximum =100
[(0.7 x 10)+(0.25 x 5)+(1.0 x 3)]/18 = 0.625, category grade = 0.625 x 100=62.5

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 Gradebook setup)

Assignment Grade Earned Max possible points Normalized grade Weight
1 80 100 80/100=0.8 2.0
2 45 50 45/50=0.9 1.0
3 95 100 95/100=0.95 2.0
4 90 100 90/100=0.9 3.0

Calculation:

[(0.8 x 2.0)+(0.9 x 1.0)+(0.95 x 2.0)+(0.9 x 3)] / 8.0 = 0.8875
Category grade for the student: 0.8875 x 100 = 88.75

Note: 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 the 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 Aggregation choices

Enter the weighted value for each category in the Weight column (click on image to enlarge)

Category Grade earned for category Max possible points for category Normalized grade Weight
Attendence 100 100 100/100=1.0 5.0
Assignments 90 100 90/100=0.9 30.0
Forums 95 100 95/100=0.95 20.0
Quizzes 85 100 85/100=0.85 45.0

Calculation:

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

 

Simple weighted mean of grades

This aggregation 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.

A1 = 70/100, A2 = 20/80, A3 = 10/10, category max = 100
[(0.7 x 100) + (0.20 x 80) + (1.0 x 10)] / 190 = 0.526, category grade = 0.526 x 100 = 52.6

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 possible 100 points will count five times more toward the final grade calculation than an assignment worth a possible 20 points.

 

Median of Grades

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.

 

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.

A1 = 70/100, A2 = 20/80, A3 = 10/10, category max = 50
(70 + 20 + 10) / 190 = 0.526, Category grade = 100 out of 190

Final grade calculation: 0.526 x 50 = 26.32

When to use Natural: When you want to generate a student’s total points earned out of the total maximum points possible

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