In a table, it can make sense to put a sum in the total row, but in some cases, ex.: when the field is a rate or a percentage, it would make more sense to put an average instead of a sum.

Student A got 70% in his exam
Student B got 80% in his exam
Student C got 90% in his exam

Knowing that the sum of all % is 240% is futile. However, it would be relevant to know that the average for this exam is 80%.
merged ideasIdea Merged with: Matrix/Table grand totals with Measures