This is just a general question..
Why do you think it is beneficial to average class data instead of drawing conclusions from only data that your group collected?
1 answer
The average of a larger group is always better than a smaller group. Think about it this way. If you do ONE test you get ONE result and your conclusions are based on that ONE result. If you do TWO tests you can get an average of the two so that if that first one is off a little the average helps correct that. The more results you have the better the average is to the correct value. Of course spurious results may be in a huge data bank but unless you have a huge number of spurious results, those get averaged out so they don't have that much of an effect on the final answer.