HOW TO TEST INCREMENTALITY BEFORE PEAK SPENDING STARTS

Summary from the TLDR Marketing newsletter

Run incrementality tests before peak season to identify which marketing channels actually generate new sales rather than taking credit for purchases that would happen anyway. Use geographic or audience holdouts to compare exposed customers against groups that don't see a channel. Aim for 20-30% holdouts and run tests for 4-8 weeks. Audit UTMs and tracking before launch. Use incremental ROAS and new customer acquisition to reallocate budget toward channels that drive genuine lift rather than those reporting the highest last-click revenue.