Attribution models

First click
This attribution gives all the credit to the first-click on an ad that led to a conversion. This means a person has clicked on an ad A in Google Search, then they saw a remarketing ad and in the end they clicked on the Shopping ad and they made the purchase. So all the credit goes to ad A.

Last click
In this case, credit goes to the last click on an ad. Take the path of a consumer from the previous point. Every ad doesn’t matter besides the one consumer clicked on last.

Linear
Now, things get a little bit more interesting for attribution models. With the linear model, every ad gets the same amount of credit.

Time decay
This model takes into consideration time and its effects on the human mind. We tend to forget about things and it’s nice when someone or something reminds us we want to buy something. The time decay attribution model thinks about this and as time goes by, it distributes less credit to older ad interactions. So when 8 days pass by from someone clicked on ad A and the Shopping ad, the Shopping ad gets half the amount of credit than the ad A.

Position-based
It does not matter how many ads crossed the buyer’s attention, the first and the last one get both 40% of credit and the rest in the middle divide 20% between them.

Data-driven
This model will work for you only when you have enough past data for Google to work with. It will give you a better perspective when deciding which ad was important and which was not as important. You can read more about data-driven attributes here.