Design a creator incrementality test in 5 steps

Design a creator incrementality test in 5 steps

Incrementality = sales that would not have happened otherwise:
— Split the audience: exposed vs geo-matched holdout
— Match on baseline sales, not population size
— Run a full purchase cycle minimum, not 7 days
— Measure the delta, not the exposed group's raw revenue
— Repeat once before you trust the lift number

A single test is a data point; the second run is what makes it a finding.

So what: last-click ROAS without a holdout overstates creator impact, often badly.

Benchmark: measured incremental lift runs 25-45% under last-click attribution (n=22 tests).