Estimation and planning

Lead times, workloads and budgets: where optimism and arbitrary figures do the most damage.

Lead times, workloads, budgets: every project promise rests on figures. The biases in this family explain why they are almost always too optimistic, even when past overruns are known, and why a first figure thrown out at random ends up imposing itself on everyone.

The most effective countermeasures are methods, not vigilance: the outside view (compare with similar projects), ranges instead of single points, measuring one's own deviations. See reference-class estimation.

The Planning FallacyWe systematically underestimate the duration, cost, and risks of our own projects, even when we know the past. Mechanism, signals, and reflexes (outside view, ranges, pre-mortem).Unrealistic optimismWe plan as if everything should go well and trouble happens to others. Mechanism, cases (UK Treasury, Weinstein), signals and reflexes to keep realistic buffers.The illusion of controlWe believe we influence outcomes that depend on chance or on other people, and we underestimate what lies beyond our steering. Where it strikes (migrations, risks, project steering), cases and reflexes.Hofstadter’s Law“It always takes longer than expected, even when accounting for Hofstadter’s law.” An empirical rule with a touch of humor, useful for understanding why adding buffer alone is not enough. Origin, cases, limits, and practical reflexes.