The best-case plan

The planning fallacy is a forecast stuck near the best week you can imagine. Similar jobs, delays, and the last time you did this are pushed out of the picture because the tidy plan feels complete. A best case is a useful ceiling. It is a poor estimate. Ask how long comparable work took, not how long this one would take if nothing went wrong. Regret often starts here: the plan was a hope, and the hope was treated as a schedule.

Cognitive bias

Planning fallacy

The planning fallacy is underestimating the time, cost, or difficulty of a task, especially one you are inside. You picture the smooth path and leave out delays that, on similar tasks, usually appear. Hope is not a base rate.

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Mini check

A project plan matches the best week you can imagine, and ignores how long similar jobs took. Which name fits?

The planning fallacy: a forecast stuck near the best case, instead of the outside view.The halo effect: one good trait is being used as proof that the budget is already sound.WYSIATI is irrelevant here, because a plan never feels like a complete story at all.System 2 has finished the job, because writing a plan is always the slow kind of thought.

Try it today

Take one deadline you set recently and compare it with how long the last similar job took.

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