5 Ways FP&A Gets Scenario Probabilities Completely Wrong

Everyone loves a scenario model. Base case, upside, downside.
But here’s the dirty secret: most FP&A teams don’t assign probabilities — or worse, they assign them blindly.

Here are five ways teams botch probability in FP&A scenario planning:

1. Defaulting to 70/20/10 Splits

The lazy template. Base case 70%, upside 20%, downside 10%. If your “probabilities” never shift, you’re not modeling risk — you’re recycling clichés.

2. Confusing Confidence with Likelihood

Just because leadership believes the upside will happen doesn’t make it more probable. Confidence is psychology. Probability is math.

3. Ignoring Correlated Risks

You can’t assign independent odds to drivers that move together. If churn rises, pipeline usually falls. Probabilities must connect, not sit in silos.

4. Forgetting the Fat Tails

Markets don’t follow neat bell curves. Black swans exist. Assigning a “1% chance” to systemic shocks ignores both history and reality.

5. No Backtesting

If you never compare assigned probabilities to actual outcomes, you’re just guessing louder. Calibration only comes from confronting your misses.

Why This Matters

Bad probability assignments create fake certainty. They don’t just mislead — they steer decisions into blind risk.

At The Schlott Company, we help CFOs build scenario planning systems where probabilities aren’t arbitrary. We calibrate them with real data, link them across drivers, and backtest relentlessly.

Because scenario planning without credible probabilities isn’t forecasting. It’s theater with a spreadsheet.