In this purchase path, the consumer does a search, clicks on an ad, and on the same day makes a purchase. Then that same consumer, without the need of additional advertising, makes a second purchase over a week later. A couple days after that, they make another purchase
a) In this attribution rule, you are choosing to give the ad that was responsible for the first sale credit for the future sales as well. The argument for this rule is that without being there during their first search, you may have not gotten the initial sale and therefore would not have received any of the future sales either.
b) In this attribution rule, you are giving the search ad credit for only the sale generated on the day it was clicked. The argument for doing this is that you believe the ad should only get credit for a sale you can directly tie it to.
c) In this attribution rule, you are giving the search ad complete credit on the day it was clicked and some additional credit for the future sales that were generated as well. The argument for this rule is that you believe without the initial ad, the 2nd and 3rd sales may not have occurred and therefore you want to give some, but not all, credit back to the initial ad.