Trading Outcome Bias / 交易结果偏误

Definition

Trading outcome bias is the error of judging a decision mainly by the profit or loss that followed, rather than by the information, sizing, risk limits, and process available when the trade was made.

Current Synthesis

EP95 makes the bias visible through a lucky recovery. Kurumi abandons her intended exit, endures a painful reversal, hopes for a rebound, and eventually profits. The favorable result then teaches the wrong lesson: waiting and rule-breaking appear validated, so later confidence and size increase.

The corrective is not to ignore results. It is to evaluate them across comparable repetitions while separating decision quality from randomness. A moved stop can remain a poor decision even when price reverses; a planned small loss can remain a sound decision even when the asset later rebounds.

Key Claims

• One profitable trade cannot validate the process that produced it.
• Lucky recovery can reinforce overconfidence more strongly than an immediate loss.
• Moving a stop changes the ex-ante risk contract rather than merely waiting for more information.
• Decision review should preserve the original thesis, evidence, size, and invalidation rule.
• Hit rate must be interpreted with payoff ratio, drawdown, costs, and ruin risk.
• Authority or another trader’s profit does not transfer their suitability, information, or risk capacity to a follower.

Evidence

Lucky recovery rewards weak process

• EP95 says Kurumi’s first trade recovers after she abandons her original plan, and subsequent profit strengthens belief in waiting through losses.

Stop movement judged by process

• EP95 explicitly distinguishes a favorable rebound from proof that cancelling or lowering a stop was correct.

Repeated-game evaluation

• EP95 argues that win rate alone is incomplete and should be paired with the size of wins and losses.

Counterevidence & Qualifications

Outcome information still matters: repeated losses can reveal a bad model, poor execution, or changed regime. The bias lies in letting one realized path erase what was knowable before the trade, not in refusing to learn from results. The source offers a fictional teaching case rather than audited trade records, and it does not specify a universal optimal stop or payoff ratio.

What Changed

• Created a trading-specific outcome-bias page from the episode’s lucky-recovery and moved-stop examples.
• Connected decision quality to repeated-game evidence rather than single-trade vindication.

Related Concepts

• Behavioral Investing Biases - broader cluster including confirmation bias, overconfidence, anchoring, and loss aversion.
• Stop-Loss Discipline - precommitted exit process that outcome bias can weaken after a lucky rebound.
• Investment Decision Logging - preserves the ex-ante reason and invalidation rule for later review.
• No-Prediction Trading - evaluates a bounded system across many outcomes rather than demanding certainty from one trade.
• Position Sizing - keeps random adverse outcomes from becoming irreversible.
• 沉没成本困局 / Sunk Cost Entrapment - past loss can distort future exposure after outcome bias has normalized waiting.