AdWords has an "Impr. assisted conv." column which you can add to reports. For this metric, does an ad/keyword/etc. get credit as assisting in a conversion due to having been seen by the user regardless of how the last click to the website happens (e.g. SEO, direct, etc.), or does the last click have to be a click on an AdWords ad?
I had trouble finding anything authoritative that directly answered this question.