Customer question
“Would these customers have converted anyway?”
What this solution does
Attribution tells you which ads got credit for a sale. Incrementality tells you whether the ad actually caused the sale, by comparing against people who saw no ad at all.
Specifically, it answers: Of the conversions a platform attributes to advertising, how many actually happened because of the advertising, versus how many would have happened regardless?
How it works
A treatment group is exposed to advertising and a control group is deliberately withheld from it (a holdout); comparing conversion rates between the two groups reveals the incremental effect the platform-attributed number does not.
Data requirements
- A genuine, sufficiently sized holdout/control group
- Randomised or matched assignment to treatment and control
- Conversion tracking consistent across both groups
- Platform-attributed conversion figures for comparison
Discovery questions
Can a true holdout group be created, or only a geographic/time-based proxy?
A true randomised holdout gives the cleanest causal estimate; proxy designs (geo-based, time-based) introduce more assumptions and potential bias.
How large does the holdout need to be to detect a meaningful effect?
Underpowered tests can fail to detect real incrementality, leading to false conclusions that a channel doesn't work.
How will stakeholders react to incremental ROAS being lower than platform-reported ROAS?
This is usually the most contentious moment in an incrementality engagement, and needs to be set up as an expectation early.
Build an experiment
Generate synthetic data
Data readiness
Run model / simulation
Results
Business ⟷ Technical interpretation
Of the platformAttributedConversions conversions the platform attributed to this campaign, only incrementalConversions appear to be genuinely incremental — the rest would likely have happened anyway. Attribution is not causation.
Shown as a template — the highlighted tokens are filled in once the model has been run.
What would you do next?
- Recalculate media efficiency using incremental ROAS instead of platform-attributed ROAS
- Run incrementality tests periodically, as true incrementality can shift with market conditions
Solution & vendor landscape
Implementation approaches