Run a small geographic ad holdout
Design a regional comparison that can inform a spending decision.
Choose markets by baseline behavior
Compare regions with similar historical demand, contribution, and operating constraints. A region with a major store opening or holiday schedule is a weak comparison for a stable market.
Write down the change and the outcome
Decide which campaign will be reduced in the test region and which will remain stable in the comparison region. Use total qualified sales or contribution from both areas rather than attributed orders alone.
Account for spillover before interpreting the result
Check whether media, shipping geography, or customers routinely cross regional boundaries. Compare pre-test and test-period differences, and note other changes such as stockouts. With very few regions, treat the result as directional.
Try a related tool
Compare revenue per advertising dollar with the return needed to cover ad spend. Enter net revenue and contribution margin before ads.
