Learn incrementality
Guides for app marketers, each built around a question people ask.
Eight guides that take incrementality from definition to decision: what it is, the main test types, how to size a holdout, how to read results, what Meta, Google and Apple offer, cannibalisation, MMM and MTA, and how to move budget.
Which guide do you need?
- 01What is incrementality in app marketing?Incrementality in app marketing explained: the share of installs and revenue your ads really caused, how it differs from attribution, and how to measure it.
- 02Holdout, geo lift, ghost ads, PSA and on/off testsCompare incrementality test types for app marketers: user holdouts, geo lift, ghost ads, PSA and on/off tests, plus how to run a geo lift test for installs.
- 03How big should my holdout group be?How to size an incrementality holdout for an app: control conversions needed, and how holdout share, install rate and expected lift set the test length.
- 04How to read lift test results without fooling yourselfHow to read an incrementality lift test: lift, confidence interval, p-value and incremental installs, the mistakes that turn noise into wins, what to report.
- 05Incrementality on Meta, Google and Apple Search AdsHow to test incrementality on Meta, Google App Campaigns and Apple Search Ads: what each platform's lift tools offer, their published rules and the fallbacks.
- 06Which UA campaigns are cannibalising organic installs?How to identify which UA campaigns are cannibalising organic installs: brand search and retargeting patterns, a four-step data check, and how to test it.
- 07MMM vs MTA vs incrementality testingMedia mix modelling, multi-touch attribution and incrementality tests compared for app marketers: what each measures, the data needed, how they fit together.
- 08How to act on incrementality resultsTurn incrementality test results into budget decisions: incremental CPI and iROAS by channel, moving spend in steps, when to retest, and reading CTV and brand.
Questions
What is incrementality in app marketing?
Incrementality is the share of conversions that would not have happened without the ad. It is measured by comparing people who could see the ads with a similar group who could not, so it captures what the ads changed rather than what they were credited with.
Is attributed the same as incremental?
No. Attribution credits a campaign when a user touched an ad before installing, even if that user would have installed anyway. Incremental installs are only the ones the ads caused, so they are always equal to or fewer than attributed installs.
How big should my holdout group be?
Big enough that the control group collects enough conversions to detect the lift you care about within the time you can wait. Lower conversion rates and smaller expected lifts need bigger holdouts or longer tests; the holdout simulator on this site shows the trade-off.
Are the numbers on this site real benchmarks?
No. Every number is sample data for a made-up app, chosen to show how the method works. Your own incrementality depends on your app, channels and audience, so measure it with your own test.
What is incremental ROAS?
Incremental ROAS (iROAS) is the revenue from conversions the ads caused, divided by spend. It is lower than attributed ROAS whenever some attributed conversions would have happened anyway, and below 1x the campaign returns less than it costs.