Spot the hidden assumption baked into a forecast
Every forecast smuggles in assumptions the spreadsheet doesn't show — until the wrong one breaks everything downstream.
- Use it for
- Anyone relying on a forecast or projection who wants to know what it's quietly assuming.
A forecast's formula is visible, but the assumptions baked into its inputs — growth continuing at the current rate, no seasonal effect, behavior staying constant — usually aren't stated anywhere, which means the forecast can look precise while quietly depending on something nobody actually checked. This prompt surfaces the load- bearing assumption before the forecast gets used to make a real decision.
When not to use this
For a rough, informal estimate nobody's going to act on directly, this scrutiny is more than the stakes warrant. This is for a forecast a real decision will actually be based on.
Did this work?
You can name the specific assumption the forecast depends on most, and roughly how much the result would change if it turned out wrong.
Tested on claude-opus-5. Evidence status is draft; it moves to battle-tested only on recorded runs, never by hand.