Ad waste glossary

The vocabulary of honest ad measurement, defined in plain language. Each term links to a full explainer with detection methods and worked context.

Ad cannibalization
Cannibalization is the gap between attributed conversions and incremental conversions, expressed as a percentage. A campaign with 60% cannibalization gets credit for 60% of orders that other channels would have produced for free.
Creative fatigue
Creative fatigue presents as rising frequency, climbing CPM, falling CTR, and rising CPA on stable audiences. It's caused by the audience seeing the same creative too many times.
Holdout experiment
A holdout experiment is the gold-standard incrementality measurement. The platform randomly assigns a portion of the audience to a control arm; the operator compares conversion rates between arms.
Incrementality
Incrementality is the difference in conversions between an audience exposed to advertising and an otherwise-equivalent audience that was not. The cleanest measurement comes from a randomised holdout.
True ROAS
True ROAS equals incremental revenue divided by ad spend. Incremental revenue is measured by holdout experiments, not estimated by an attribution model.