Last-click attribution

Last-click is the simplest attribution rule: whoever got the final click before the purchase, install or sign-up gets all the credit. It is easy to implement and understand, which is why it became the default in many analytics tools, affiliate programmes and app install deals.

Its weakness is that it rewards being last, not being useful. Brand search ads and retargeting ads, which catch people already intending to buy, look brilliant; upper-funnel video or display that created the interest looks worthless. It also encourages fraud: Click injection, click spamming and cookie stuffing all work by planting a last click.

Most platforms now offer alternatives, including multi-touch and data-driven models, and marketers increasingly validate channel value with incrementality tests and marketing mix modeling. Last-click remains common in contracts because it is unambiguous, so it is worth pairing with short lookback windows and fraud checks.

Think of it like this

Last-click attribution is like giving the whole relay-race medal to the final runner, forgetting the three who ran before.

An example

A customer sees a YouTube ad, reads a review site, then clicks a branded search ad and buys a $400 phone. Last-click credits the entire $400 to the search ad.