Incrementality experiments differ from A/B experiments in what way?

Incrementality experiments specifically measure the causal impact of advertising by comparing a group exposed to ads against a control group that is intentionally not exposed. This reveals how many conversions would not have happened without the ads, thus determining the true incremental value. A/B experiments, conversely, compare different versions of an ad or campaign element (e.g., headline A vs. headline B) to see which performs better among those exposed to ads. While both can use holdback groups, incrementality focuses on the net effect of ads versus no ads, whereas A/B testing optimizes within an ad-exposed audience. Incrementality often requires more sophisticated analysis due to the nature of isolating the ad effect from organic conversions.