Just from all of the clicks and earnings over that period of time. So total earnings from all affiliates divided by total clicks from all affiliates over the prescribed amount of time, multiplied by 100. I prefer looking at the 3 month EPC, because 7 days is such a short window.
EPC stands for "earnings per click". EPC is the ultimate test to tell which of the affiliate merchants you're promoting is performing the best. It can also show you the duds. Is an affiliate program that pays $100 commission better than a program that pays $5 commission? Maybe. Maybe not. You can find out by calculating the EPC. To calculate the EPC, you simply divide the commission generated by the number of clicks. For example, if you receive a commission of $20 after sending 100 clicks (visitors) to the merchant... Divide $20 by 100 = 0.20. Your EPC is 20 cents per click. so use this method to calculate your 3 months EPC