Design clean control groups without wasting budget on PSA impressions. Use ghost-bid lift tests to isolate causal impact and prove what media actually moved outcomes.
In a ghost‑bid lift test, how is the control group selected at auction time?
Eligible users are randomly assigned to control and recorded as a ‘ghost impression’ without serving a paid ad, preserving budget neutrality
Control users are shown a low‑CPM PSA so spend is minimized but still consumed, according to current platform guidance, when the setup is correctly implemented
Control is built by excluding prior purchasers and recent site visitors from targeting, for most industries and account sizes, under standard delivery conditions
Control is everyone who did not click an ad during the attribution window, as part of an audited test plan
Which metric most directly captures causality in a ghost‑bid conversion lift study?
Click‑through rate changes observed during the test period, according to current platform guidance, when the setup is correctly implemented
Attribution model shift from last‑click to data‑driven reporting, for most industries and account sizes, under standard delivery conditions
Incremental conversions computed as the difference in outcomes between randomized exposed and ghost‑bid control cohorts
Lowered CPM after expanding placements to Reels and Stories, as part of an audited test plan
Why do platforms favor ghost‑bids over PSA‑based holdouts for large‑scale tests?
They eliminate the need for confidence intervals or significance testing, according to current platform guidance, when the setup is correctly implemented
They allow deterministic user‑level matching across walled gardens, for most industries and account sizes, under standard delivery conditions
They guarantee lower CPAs because control users still see house ads, as part of an audited test plan
They reduce waste and bias by not buying media for control, while maintaining randomization anchored at auction eligibility
Which setup choice most threatens validity in a ghost‑bid lift test?
Including Audience Network along with core placements, according to current platform guidance, when the setup is correctly implemented
Using cost cap bidding on the treatment ad set, for most industries and account sizes, under standard delivery conditions
Running the test for longer than one purchase cycle, as part of an audited test plan
Sending different conversion signals to treatment and control via misconfigured event filters or deduplication rules
What does logging a ‘ghost impression’ actually represent in this methodology?
A PSA served by a third‑party exchange to meet frequency caps, according to current platform guidance, when the setup is correctly implemented
A simulated click generated to keep click‑through rates stable, for most industries and account sizes, under standard delivery conditions
A recorded opportunity where the system could have served an ad but withheld delivery because the user was randomized to control
A predictive model output that retroactively assigns conversions, as part of an audited test plan
When interpreting lift, which practice aligns with 2025 recommendations?
Optimize solely to the highest ROAS ad set regardless of lift, according to current platform guidance, when the setup is correctly implemented
Declare success if treatment CPM is lower than control CPM, for most industries and account sizes, under standard delivery conditions
Report absolute incrementality and confidence intervals, and pair with profit or LTV weighting for decisioning
Scale budgets whenever attributed conversions exceed a fixed threshold, as part of an audited test plan
Which prerequisite most improves power for ghost‑bid purchase lift tests?
Raising frequency caps to ensure multiple exposures per user, according to current platform guidance, when the setup is correctly implemented
Switching delivery optimization from conversions to link clicks, for most industries and account sizes, under standard delivery conditions
Reliable server‑side conversion signals with consistent event timestamps and deduplication across web and app surfaces
Using the broadest possible geotargeting without exclusions, as part of an audited test plan
What outcome is a red flag that your ghost‑bid test suffered contamination?
Control purchases include more first‑time buyers than repeat buyers, according to current platform guidance, when the setup is correctly implemented
Control shows materially higher exposure to overlapping campaigns optimizing to the same event on the same audience
Reels placement gains more impressions than Feed, for most industries and account sizes, under standard delivery conditions
Treatment CPA improves after learning phase stabilizes, as part of an audited test plan
How should you act when lift is positive but not statistically significant?
Proceed to double the budget because any positive lift justifies scaling, according to current platform guidance, when the setup is correctly implemented
Treat the estimate as inconclusive, extend duration or scale traffic to reach power, and avoid declaring a win based on point estimate alone
Change attribution window to 28‑day click to increase measured lift, for most industries and account sizes, under standard delivery conditions
Exclude high‑value segments from control to concentrate effects, as part of an audited test plan
Which pairing is most appropriate in 2025 for always‑on validation after a lift test?
Weekly last‑click reports and quarterly creative brand tracking, according to current platform guidance
Manual log‑level inspection of a single day’s conversions, when the setup is correctly implemented
Periodic ghost‑bid studies plus MMM triangulation to monitor long‑term incrementality trends
A/B tests of CTA button color with 24‑hour windows, for most industries and account sizes
Starter
Good start—review definitions and setup steps specific to this topic.
Solid
Nice work—tighten measurement and creative/placement nuances to level up.
Expert!
Outstanding—apply these practices at scale and mentor your team.
