Level: Advanced
Geo-testing runs a campaign in some geographic markets while holding others out entirely, comparing results between them to isolate the campaign's genuine incremental effect.
Randomize or Carefully Match Test and Control Regions
Regions need to be genuinely comparable in size and baseline behavior for the comparison to be meaningful, whether through random assignment or careful matching on historical performance.
Measure the Gap in Overall Business Results, Not Just Ad Metrics
The real test is whether total conversions or revenue differ meaningfully between the exposed and held-out regions, not just whether ad-platform-reported conversions differ.
This Approach Works Well When Individual-Level Tracking Is Unreliable
Geo-testing sidesteps privacy-driven tracking limitations entirely, since it measures aggregate regional outcomes rather than depending on individual user-level attribution.
Next step: Use the Sales Letter Writer to if a geo-test reveals weaker-than-expected incremental lift, consider whether the creative running in the test region was genuinely strong enough to move behavior, separate from any targeting or budget factors.