Reliable forecasts come from historical system behavior rather than conjecture about individual work items.
- When predicting outcomes, models based on historical system behavior outperform models based on speculative task estimates.
- Because speculative estimates introduce large variance and bias.
- When many tasks are estimated, variance explodes. 1
- When predicting delivery based on historical throughput, variance exists, but it is bounded by observed system behavior.
- Speculative estimates suffer from Optimism Bias
- Speculative estimates suffer from Unknown unknowns. Estimation assumes complete task knowledge which is rarely ever known.
Lines of Inquiry
- Right now, this principle is currently heavily skewed toward estimation and forecasting, though I believe it applies at a more general level. Working to make this notes more generic and push specifics down to Probabilistic Forecasting
- Will need to handle moving the citation to the appropriate place as well
| Domain | Evidence | Relationship | Speculation |
|---|---|---|---|
| Probabilistic Forecasting | Throughput | > | Estimates |
| Hypothesis-Driven Development | Experiments | > | Opinions |
| Evidence-Based Management | Metrics | > | Intuition |
| Customer Discovery | Validated customer pain | > | Guessed demand |