Overconfidence bias is the tendency to overestimate the accuracy of your own knowledge, predictions, and abilities — one of the most robust and replicated findings in psychology.

Three Types

• Overprecision: Excessive certainty in the accuracy of your beliefs — "I'm 90% sure" when you should be 60% sure
• Overplacement: Believing you're above average — 93% of drivers rate themselves above average
• Overestimation: Overrating your actual performance or output on a specific task

Where It Causes Real Damage

• Trading: Overconfident investors trade too frequently and earn below-market returns
• Startups: 90%+ of new businesses fail — overconfidence in their own plan is a leading factor
• Medicine: Diagnostic overconfidence leads to under-testing and missed diagnoses
• Project management: Timelines and budgets are almost universally underestimated

Calibration Tool

Track your predictions and their outcomes. Prediction tracking is the fastest known method for improving calibration.

Reference:

Wikipedia: Overconfidence Effect

https://en.wikipedia.org/wiki/Overconfidence_effect