Glossary
Last-click attribution
A model that gives all credit for a conversion to the final click before it. It is the most common model and gives no credit to earlier ads in the journey.
Also called: last touch, last-click
Last click gives one hundred percent of the credit to the last thing the customer touched. Everything earlier gets nothing.
It persists because it is unambiguous, cheap to compute, and impossible to argue with in a meeting. Every platform can produce it, the numbers reconcile, and nobody has to defend a weighting scheme. Those are real advantages and they explain its survival better than any measurement argument.
What it does to your budget. It systematically overpays whatever sits closest to the purchase and underpays everything that created the demand. Branded search looks extraordinary. Retargeting looks extraordinary. The channel that made someone aware you exist looks like a cost centre, gets cut, and several months later the bottom-funnel channels quietly get worse — because they were harvesting demand that something upstream was creating.
That lag is what makes the error so durable. The cut looks correct for a quarter.
The reasonable position. Last click is a fine report and a poor decision rule. Use it to see what happened at the end of the journey, where it is genuinely accurate. Do not use it to decide what to fund, because it cannot distinguish a channel that caused a sale from one that was merely present at the end.
For that you need incrementality — and the two will disagree, which is the useful part.
Do not confuse with
Close enough to get mixed up, different enough that the mix-up costs something.
- Assisted conversion A touchpoint that appeared earlier in a converting journey without being the last interaction, such as a display ad seen two days before a branded search.
- Attribution model The rule that splits credit for a conversion among the touchpoints before it. Last click, linear and data-driven models each give a different split.
- Attribution window The period after an ad click or view during which a later conversion still counts for that ad. A conversion after the window closes goes to another source.
- Incrementality The share of conversions that a marketing activity caused, compared with what would have happened without it. Holdout tests and geo experiments measure it.
- Marketing mix modelling A statistical model that estimates each channel's contribution from aggregate spend and outcome data over time, without tracking individuals. Often called MMM.