Attribution
Attribution determines which ad touchpoint receives credit for a conversion, using last-click, first-click, time-decay or data-driven models.
What does Attribution actually mean?
Attribution is the methodology for assigning credit to ad touchpoints in the buyer journey. The default in most ad platforms is last-touch (sometimes last-click) attribution: the most recent ad-clicked-before-purchase gets full credit.
Real buyer journeys are messier. A user might see a TikTok ad, search the brand on Google, click a Meta retargeting ad three days later, then convert. Last-touch credits Meta with 100%; the truth is closer to one-third each. This systematic over-crediting of bottom-funnel platforms is why most large advertisers use MMM (media mix modeling) or incrementality testing alongside platform-reported attribution.
In 2026, data-driven attribution (DDA), Google's default, uses ML to distribute credit across touchpoints based on observed conversion paths. It's better than last-click but still confined to clicks the platform sees. View-through attribution adds impression-based credit but inflates platform reporting further.
Example
A user sees a TikTok ad, searches the brand on Google, clicks an Instagram ad, then converts. Last-click attribution credits Instagram 100%. DDA might credit TikTok 30%, Google 20%, Instagram 50%.
When it matters
Attribution determines budget allocation. Brands that trust platform-reported attribution overspend on bottom-funnel; those that triangulate with MMM and holdouts allocate better.
Related terms
MMM
MMM is a top-down statistical method that estimates each marketing channel's contribution to revenue using time-series data. It's privacy-friendly and attribution-window-agnostic.
Incrementality
Incrementality measures the additional revenue ads generate vs. what would have happened without them, usually measured via holdout tests or geo-experiments.
Blended ROAS
Blended ROAS is total revenue divided by total ad spend across all channels. It's equivalent to MER, the honest top-down ad efficiency metric.
Pixel
A pixel is a JavaScript snippet on your website that sends user behavior events (pageview, add-to-cart, purchase) back to ad platforms.
CAPI
CAPI sends conversion events directly from your server to the ad platform, bypassing browser-side limitations of pixel tracking.
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