The aggregation dropdown menu lets you choose the aggregation strategy that will be used to calculate each participant's overall grade. There are different options:
Mean of grades: The sum of all grades divided by the total number of grades.
Weighted mean: Each grade item can be given a weight, which is then used in the arithmetic mean aggregation to influence the importance of each item in the overall mean.
Simple weighted mean: The difference from Weighted mean is that weight is calculated as Maximum grade - Minimum grade for each item.