## How are averages calculated in the grade book?

Information about calculating averages or aggregation methods in the Moodle grade book program.

### How are averages calculated in the grade book?

The Moodle program has several different ways that can be used to calculate the averages of the grades in the course and grades in sub-categories. These different ways of calculating the grades are called different aggregation methods.

There is a help button beside the place where you choose the aggregation (averaging) method. Clicking on this button will give very useful information. Three aggregation methods are mentioned here.

1) Mean of grades. This aggregation method will do a straight average of all the grades in the category. If all the grades items are graded on the same scale (for example, out of a possible 100 points) and all items are worth the same amount, this is the aggregation method you should use.

2) Weighted mean of grades. This aggregation method allows you to select how much weight (how important) each item in the category should receive. If you have several grade items, but some are more important than others (count for a bigger percentage of the grade) this is the aggregation that you should use. If you create a grade item or a sub-category in a category where the "Weighted mean of grades" is the aggregation method, the program will ask you for the weight that should be given to the item or the sub-category. Be sure you fill in something if it should count in the overall average, since if you don't fill in anything (or leave the weight as zero) the item will not count for or against the student.

For example, if you have a quiz and a final exam, and the quiz counts 25% and the final exam counts 75%, then you an give the quiz a weight of 25 and the final exam a weight of 75.
If a student makes 50% on a quiz and 100% on the final exam, if the aggregation method is "Mean of grades" the Moodle program will calculate an aggregate grade of 75%. However, if the weighted mean of grades is used (with the weightings given above) then the aggregate grade will be 87.5 (75% of 100 = 75 plus 25% of 50=12.5 = 87.5).

The weights do not have to add up to 100%. Thus, giving the quiz a weight of 10 and the final exam a weight of 30 (3 times as much) will produce the same result. Thus, in the example given above, the weights of 10 and 30 would still produce an average grade of 87.5.

Please note that if the maximum grade on the quiz is 20 and the student gets 10 out of 20 on the quiz and the student gets 100 our of 100 on the exam, then the grades would be the same as those calculated above, since 10 out of 20 is still 50%. Thus, specifying the maximum grade that can be received on an assignment is important. If you want to give extra credit and the maximum extra credit is 10 points, don't specify that the maximum grade is 110. (The program tries to protect you by not letting you put more than 100 points for the maximum grade.) If you did specify a maximum of 110, the Moodle program would calculate the average for that person as being 90.9% even though they made 100 on the test (since they only got 100 out of a possible 110 points).

3. Simple weighted mean of grades. With this aggregation method, you don’t specify the weight to be given to an assignment; rather, the Moodle program will assign different weight to different assignments based on the maximum number of points that can be earned for the assignment. Making 10 out of 20 on the quiz and 100 out of 100 on the exam yields the following calculation. A total of 120 (20+100) points are possible, and this student earned 10 quiz points and 100 exam points, or 110 points in all. The simple weighted mean = 110/120=90.2% or an aggregate grade of 90.2. This aggregation is useful for some people who set up their courses with a certain number of points for certain assignments. This aggregation also allows you to give extra credit by adding in extra credit as an additional grade item.

For whichever aggregation method you use, it is recommended that you check at least one or two of the grades in the class to be sure that the Moodle program is calculating the grades the way that you want them calculated.

If you are using the default setting, the averages that are given are based on the assignments that have been submitted so far. Thus, the program helps give students an indication about their current standing in the course. However, the failure of students to turn in an assignment does not hurt their grade until you give them a zero (or some similar low grade).

The Moodle program does aggregation by doing calculations with the numbers that you enter for various assignments. However, if you wish you can have the program display letter grades (rather than numbers) for any items or categories. That option is explained in a Wiki below.

There seem to be over 100 different ways that Eckerd professors use to assign the final grades in courses. If one or more of the standard ways of aggregating the grades doesn't do what you would like for it to do, or if you have questions, or if you want for me to check and verify that the calculation is being done the way you want for it to be done, please contact me and I will be glad to help you.