Incrementality

Incrementality is the question that belongs under every effect measurement: what happened that would not have happened without the campaign? A sale that was coming anyway and happened to pass through an ad is not an effect but an attribution. The instrument is the experiment: a test group that sees the campaign against a comparable control group that does not, with the difference as the real effect. Incrementality is thus the correction on attribution, which mostly records who touched the buyer last. The rule is strict but simple: the better a channel scores in attribution, the more it needs the incrementality test.

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