Attribution Basics

Attribution decides which marketing touchpoint gets credit for a conversion. Two ideas drive it: the lookback windowlookback windowHow far back in time an attribution model considers marketing touches when crediting a conversion. (how far back to consider touches) and the model (how to split credit among them).

First-click hands everything to the touch that first found the customer (great for rewarding discovery, blind to what closed the deal). Last-click does the opposite: simple and predictable, but it ignores everything that warmed the user up. Data-driven, now the GA4 default, shares credit using observed patterns, harder to explain but often fairer.

This is also why two tools rarely agree: a click-based ad platform and a session-based analytics tool use different windows and models, so their conversion counts legitimately differ.