Affects Version/s: 11.4, 12.5, 19.0, 20.0 [Tentative]
When using categories & weights with an extra credit category, the course grade does not compute correctly when the student has earned extra credit but doesn't yet have grades in all gradebook categories. The course grade is skewed high until the student has grades in all gradebook categories.
I replicated in 11.4, 12.5, 19, and 20 master.
Here's an example of how to replicate:
1. In an empty course, set up Gradebook with a few categories & weights plus an Extra Credit category. For example:
Homework = 20%
Labs = 30%
Exams = 50%
Extra credit = 5%
2. Create 1 Gradebook item in each category, such as:
HW 1 (100 pts) - in Homework category
Lab 1 (100 pts) - in Labs category
Exam 1 (100 pts) - in Exams category
Practice sets (100 pts) - in Extra Credit category (Note: Do not mark the ITEM as extra credit; just put it in EC category.)
3. For one student, enter a perfect score for the EC item and for the HW1 item, like so:
HW 1 = 100
Practice sets = 100
Lab 1 = LEAVE BLANK
Exam 1 = LEAVE BLANK
4. Look at the student's course grade – it should be 105%. But it is showing as 125%.
5. Now enter a perfect score for the Lab 1 item. The student's course grade should be 105%. But now it's 110%.
6. Finally, if you give the student a perfect score on the Exam 1 item, the course grade will be correct: 105%.
The current formula for calculating the course grade when some categories are empty appears to be something like this:
(cat1avg*cat1weight + cat2avg*cat2weight + ECcatavg*ECweight) divided by (cat1weight + cat2weight)
To calculate correctly, the EC part should not be in the numerator, but instead should be added to the final total, like this:
((cat1avg*cat1weight + cat2avg*cat2weight) divided by (cat1weight + cat2weight)) + ((ECcatavg*ECweight) divided by 100)