Estimation Bias

Systematic errors in estimation that cause consistently optimistic or pessimistic predictions. The most common form is optimism bias — the tendency to underestimate effort and duration, often called the 'planning fallacy.' Other forms include anchoring bias (being swayed by the first estimate heard), status quo bias (anchoring to historical estimates without accounting for new complexity), and the Dunning-Kruger effect (overconfidence in areas of low competence). Planning poker directly addresses anchoring bias through simultaneous card reveal. Other mitigations include reference class forecasting (comparing to similar past work), three-point estimation, and explicitly asking 'what could go wrong?' before finalizing an estimate.