Where should you actually be unsure?

Every input has a guess and a range. A tornado chartA bar-per-input chart, sorted by swing magnitude — the widest bar is the input that moves your answer most. The shape rolls down to a point like a tornado. ranks your inputs by how much they move the answer when each alone slides from low to high. Spend your precision where the bar is fat; stop worrying about the rest.

Model
Outcome = Monthly visitors × Sign-up rate × Activation rate × Annual revenue per user
Baseline (all inputs at base): 144.0k
Worry first about Sign-up rate — its low/high spans 72.0k–288.0k (150% of baseline).
1
150%swing
72.0k288.0k
2
150%swing
72.0k288.0k
3
140%swing
86.4k288.0k
4
100%swing
96.0k240.0k
One-at-a-time sensitivity on a multiplicative model — bars rank inputs by absolute swing of the outcome from low to high.