What is last-click attribution?

Last click is the simplest attribution rule: whichever tracked click came last before the conversion gets 100% of the credit. It is what Google Analytics reported for years and what many businesses still steer by, because it needs no model and produces a clean number per channel.

The last click is usually the final step before a purchase, not what caused it. A customer who saw a TV spot, searched the brand name and clicked the first ad is counted as a branded-search sale, and TV gets nothing. Retargeting, which by definition reaches people already interested, looks like the most efficient channel in the account. Meanwhile any channel without a click, from TV and radio to out-of-home and most of social's demand effect, is invisible. Cookie loss and privacy rules shrink the tracked share further every year.

The predictable result: a last-click budget drifts toward the bottom of the funnel, buying sales that would have happened anyway, while the channels that created the demand are cut because they never got the click.

For optimizing inside a platform, the platform's own attribution is the right tool and better than last click across tools. For budget decisions across channels, a marketing mix model measures what each channel caused above the baseline from aggregated spend and sales, with no click required, so TV and search are judged on the same terms. The platform numbers are not thrown away; they inform the model's priors.

• Attribution: Crediting conversions to the touchpoints that preceded them. Great inside a platform, not a currency across them.
• Incremental sales: The sales a channel caused that would not have happened without it. The only kind of sales worth paying for.
• Marketing mix modeling (MMM): The statistical method behind everything else on this list: spend in, sales out, every channel on equal terms.
• ROAS: Return on ad spend: revenue per unit of spend. Useful, as long as you know which ROAS you are looking at.

Go one level deeper: Why Google Analytics and Meta report different numbers. Or go back to all terms in the glossary.