Lookback Window

A lookback window is the fixed span of time an attribution model looks back over to decide which touchpoints before a conversion still deserve credit.

A lookback window is a parameter every attribution analysis needs, hidden or explicit: it must decide whether a touch that happened, say, ninety days ago still has a share in today's conversion, or is far enough back to be ignored. Choosing its length is a decision, not a natural number; a short window drops the top-of-funnel channels that planted the seed early and pushes credit toward channels near the purchase, while a long window does the opposite and may count irrelevant old touches. So the window's length should fit the real purchase cycle: a few days for an impulse buy, several weeks to months for an expensive or subscription purchase. A lookback window should not be confused with a conversion window; that one is the deadline to complete a defined action, this one is the horizon for crediting the past.