Conversion Lift
Conversion Lift is Meta's native incrementality test — a randomized holdout that measures the incremental conversions ads caused, rather than the platform-attributed conversions.
Conversion Lift runs as a managed experiment inside Meta Ads Manager. You define a campaign, Meta holds out a control group of users who never see the ads, then compares conversion rates between the exposed and holdout groups. The difference is the incremental lift caused by the campaign.
Conversion Lift tests typically require a Meta rep to set up and need sufficient spend ($20k+ per test) and conversion volume to reach statistical significance. They are the most rigorous answer to "did Meta actually cause this revenue?"
Equivalent tests exist on other platforms: Google Ads Uplift studies, TikTok Lift, LinkedIn Brand Lift. All measure the same thing — incremental conversions rather than reported conversions — and all produce lift numbers dramatically lower than platform-reported attribution. Plan on iROAS being 50–70% of reported ROAS for Meta retargeting, 70–90% for Google Search non-brand.