The Illusion of Skill

The evidence

Most active traders underperform the index after costs, yet most traders believe they are above average (the better-than-average effect). In rising markets, everyone's results look like skill; Kahneman's formulation: "success = talent + luck; great success = a little more talent + a LOT of luck." Confusing a bull market with ability is the most expensive identification error in markets.

The calibration cure

Calibration: does your stated confidence match your hit rate? If you are "80% sure" ten times and right six, you are not 80%. Track predictions with confidence levels in the journal and score them quarterly. Calibrated traders size honestly (confidence 60% → smaller size); overconfident ones size at their FEELING, which is systematically inflated.

The hot-hand check

After a winning streak, the danger is size creep: 5 wins in a row feels like skill unlocking — but at a 50% base rate, 5 straight wins happens every 32 trades (day 31). The rule: size is set by the SYSTEM, and streaks change nothing. The best performers treat hot streaks as variance to be survived humbly, not a new gear.

Sources

• Thinking, Fast and SlowDaniel Kahneman
• Overconfidence BiasInvestopedia