There are as many attribution models as there are advertisers online and with good reason: there are no right or wrong answers. What matters is what is right for your business.
The purpose of an attribution model is to link ad spend to a desired outcome. Ask yourself, what do you want: conversions, revenues, profit, a phone call? Once this relationship is established we learn about the cause (spend) to effect (revenue) ratio. This is done through detailed click profiles formed by keywords, match types, devices, user profiles, etc. for the purpose of using this information to replicate the success that happened (or to avoid failures). Your attribution model sets the rules for how this is done.
Do not make the mistake of looking at your AdWords or Analytics account and view the conversions or revenues as your accounting records, it will never match. The purpose is to find a relationship and balance between spend and outcome that is replicable. A conservative model (Google Analytics tracking) will find fewer of these relationships than a more aggressive model through AdWords All-conversions. More is always better, just adjust the targets to ensure you have a model that contributes to your company’s financial success.
Recently, your attribution model of choice just became more critical with the removal of the right side ads. There are now more clicks for the precious top four ads and way less for the bottom. Last click models have a major disadvantage since they have less data to work with and because the resulting lower bid calculations.
Attribution is a big subject, but just one in the AdWords game. Feel overwhelmed? Download our infographic that shows the signs and what you can do about it!