First-Touch vs Last-Touch Marketing Channels- Paid channels have lower visitors by First-Touch? Hi, Our hypothesis is that paid marketing channels by first-touch marketing channels have higher number of visitors, while paid marketing channels by last-touch marketing channel have lower number of visitors. To illustrate, if Visitor first intereacted with SEM-> dropped off-> Returns within 30 days via organic search, then first touch marketing channel is SEM and last touch marketing channel is Natural Search. However, we see a reverse trend than our hypothesis, i.e. paid marketing channels have a much lower visitors than non-paid marketing channels by first-touch dimension. May we know the rationale of this trend please?Also, may we know if marketing channels are attributed based on external campaign tracking codes? If the external campaign tracking codes are not implemented on all marketing channels, will we be seeing an incorrect picture for marketing channel? What is the differences between external campaign tracking codes and marketing channels? May we