[!todo] Seed note. A starting point, not a finished note yet.
The planning fallacy, named by Kahneman and Tversky in 1979, is the reliable tendency to predict that a task will go faster, cheaper, and smoother than past experience with similar tasks would justify. The tell is the skew: estimation errors lean almost entirely toward optimism rather than scattering evenly, which marks it as a systematic bias rather than ordinary noise. It persists even when the forecaster has personally watched comparable projects overrun, because the inside view fixates on this plan’s specifics and discounts the base rate. It is the error that Reference Class Forecasting is designed to correct, by forcing the forecaster to anchor on how similar projects actually turned out. Seeded from Reference Class Forecasting.