Q4 CPI shock: a scenario sheet for the reader’s own baseline
Q4 can raise CPI without changing the game. A reproducible illustrative example with editable inputs and explicit limits.
Q4 can raise CPI without changing the game. This sheet applies a multiplier the reader chooses to a baseline CPI and shows installs lost at a fixed budget.
Define the calculation before using it
Enter baseline CPI, Q4 multiplier, and fixed media budget. Compare installs before and after. Label the multiplier illustrative unless a dated internal observation supports it.
Work through the synthetic example
A 2.00 baseline CPI, 1.40 multiplier and 50,000 budget yields 25,000 installs off-peak and about 17,857 in the shocked scenario—7,143 fewer installs at the same spend.
| Output | Worked-example result |
|---|---|
| Off-peak installs | 25000.0000 |
| Shocked CPI | 2.8000 |
| Shocked installs | 17857.1429 |
| Installs lost | 7142.8571 |
Use the artifact and preserve its assumptions
Open the editable calculator to change the inputs and inspect the sensitivity view. The CSV records synthetic inputs and expected outputs; the JSON fixture keeps the equations available for reproduction. These calculations have been checked against the stated example. No measured campaign data is included.
The sensitivity rows vary only mult by 20% below and above the entered value. They are scenarios, not confidence limits or a forecast distribution. A row outside the model’s constraints is labelled rather than turned into a plausible-looking result.
Evidence and limits
Google documents budget mechanisms, not a seasonal CPI index. The multiplier is a scenario input. See Budgets overview, especially “Average daily budgets and spending limits”.
No industry Q4 CPI is asserted. Auction composition differs by network, geo and genre.
Background: A Q4 UA Budget Planning Checklist Before the Rush and Annual and quarterly UA budget planning. These existing articles provide context; the present calculation does not verify every archived claim.
No actual campaign outcome or recommended industry default is claimed.
