Measurement & attribution
Incrementality
Incrementality measures how many outcomes happened because of the media that would not have happened without it, typically via holdout or geo experiments. It is the corrective to attribution's habit of crediting media for conversions that were coming anyway.
In practice
The classic case is brand search and retargeting: heavily credited, partially non-incremental. Testing reveals how much of the reported performance is genuinely caused.
Incrementality thinking, even without formal tests, improves decisions: always ask what would have happened anyway before scaling a 'winner'.