Conditional formulas

Hey,

Not sure if the title for this thread is correct, I am not familiar with the meanings of excel jargon.

But what I am looking to do is calculate values across criteria. So I have a certain amount of test subjects, and each test subject has multiple values ('cases'?) across a certain time period (value calculated each second). I want to calculate the average across each time section, based on the condition. So all conditions '1', I want them to be averaged all together along time 1, time 2, time 3 and so on (averaged across all test subjects). This way I will be able to construct 4 lines (in a graph) in total (there are 4 conditions) that progress along a certain time length (17 seconds in the illustration). I think this is not a difficult thing to do in excel, but I just dont know how to do it.