Incrementality Testing Causal

Incrementality testing measures the true, causal impact of a marketing campaign by comparing outcomes in treated and control groups. Unlike attribution models (which guess how much credit an ad deserves), incrementality answers the counterfactual question: "How many customers would have converted without the campaign?" The core method is randomized holdout testing: a percentage of your audience doesn't see the campaign, serving as a control. After the campaign, you compare conversion rates (treated vs control), isolating the true lift.