Question: What is a geo-based experiment?
- Geo experiments use random geographic regions assigned to control group.
- Geo experiments use overlapping geographic regions that are assigned to a control or treatment group.
- Geo experiments use random geographic regions assigned to test group.
- Geo experiments use non-overlapping geographic regions that are randomly assigned to a control or treatment group.
Explanation
This method creates clean market-level comparison cells so ad impact can be measured without audience overlap. Separating locations prevents the same local demand from influencing both baseline and exposed results. Random assignment reduces bias so performance differences are more likely tied to the tested media. In Google Ads, Conversion Lift can use this structure to estimate incremental impact on offline outcomes such as store visits and store sales.
Why the other options are incorrect
Overlapping geographic regions can contaminate results because the same market influence may affect both groups.
Control group only is incomplete because lift measurement also needs a treatment group for comparison.
Test group only is incomplete because there is no baseline to measure incremental impact.
Source for verification
https://support.google.com/google-ads/answer/12003020
https://support.google.com/google-ads/answer/14097193
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