Attribution
Attribution assigns credit for a conversion across the marketing touchpoints that contributed to it. Common models: last-click, first-click, linear, time-decay, and data-driven.
Attribution is the logic by which a marketer decides which ad, channel, or campaign gets credit for a sale. The choice of model determines which channels look profitable in reports.
Last-click attribution gives 100% credit to the final touchpoint before conversion — the simplest model and the default in most ad platforms. First-click credits the initial touchpoint, useful for brand awareness work. Linear and time-decay spread credit across the funnel.
Data-driven attribution (DDA) uses machine learning to assign credit based on how much each touchpoint actually influenced conversion probability. Google's DDA is the current default in Google Ads. DDA typically shows higher credit for upper-funnel channels than last-click does — which can reshape budget decisions dramatically.
Multi-touch attribution tools (Triple Whale, Rockerbox, Northbeam) stitch attribution across platforms so you see the full path. Incrementality testing is the rigorous alternative: hold out audiences and measure the revenue lift the campaign actually caused, not just the revenue it claimed.