Definition
A PSA (public service announcement) test replaces your ads with neutral ads to estimate incrementality while keeping auction dynamics similar.
Example
Instead of pausing ads, you serve a neutral PSA creative to a holdout group and compare conversions.
How to use it
- Useful when you cannot fully turn off ads without affecting auctions.
- Interpret with care; PSA design and audience leakage can bias results.
- Ensure the PSA creative is neutral and does not change user intent.
Common mistakes
- Using a PSA that attracts clicks and contaminates the control group.
- Running tests too short to cover conversion lag.
Measured as
Measure PSA Test with a fixed attribution window, conversion event, and spend basis before comparing campaigns or creative tests.
Misused when
- Using a PSA that attracts clicks and contaminates the control group.
- Running tests too short to cover conversion lag.
Operator takeaway
- Useful when you cannot fully turn off ads without affecting auctions.
- Interpret with care; PSA design and audience leakage can bias results.
- Ensure the PSA creative is neutral and does not change user intent.
- Use PSA Test only inside a stable attribution rule, conversion definition, and time window so campaign comparisons stay honest.
- If performance changes, check whether the metric moved for a real business reason or because the measurement setup changed underneath you.
Next decision
- Read Attribution vs incrementality: what to trust, when, and how to test if the decision depends on interpretation, policy, or trade-offs beyond the raw formula.
- Decide which report owns PSA Test before comparing campaigns, channels, or creative tests.
Where to use this on MetricKit
Guides
- Attribution vs incrementality: what to trust, when, and how to test: A practical guide to attribution vs incrementality: common attribution models, window pitfalls, how MER/marginal ROAS fit in, and how to run holdout/geo tests.