What is hindsight bias in trading?
In one line: Hindsight bias is the feeling, after something happens, that you knew it all along, even though it wasn't clear at the time.
The idea
Look at any old chart. The big move looks obvious. "Of course it went up from there."
At the time, the right side of the chart was blank. Nobody knew. That gap between "obvious now" and "unclear then" is hindsight bias.
A simple example
You scroll back on a chart and spot 10 clean setups. Every one of them worked. You think, "This is easy."
But you only noticed the ones that worked. The 8 that failed don't stand out, so you skipped past them without counting.
Real record: 10 wins and 8 losses. A Win rate of about 56%, not 100%.
Why it matters
Hindsight bias causes 2 problems:
- Overconfidence. You think a method is far better than it is, then size up.
- Harsh self-judgment. After a loss, "I should have seen it" feels true. Often there was nothing to see.
Both pull you away from your rules. See overconfidence in trading.
A common mistake
Scrolling back through history and counting setups by eye. That's testing with the answers showing. Instead, use bar replay: hide the future, step forward one candle at a time, and decide before you see what happens. See TradingView bar replay and how to backtest a trading strategy.
Write your reason for each trade before the result. Then, in your journal, you can see what you actually knew at the time.
Hindsight bias has a cousin in testing called look-ahead bias: using information that didn't exist yet.
Questions
What is an example of hindsight bias in trading?
Looking back at a chart and saying "it was obvious it would drop," even though you, and most people, couldn't tell at the time.
How do you avoid hindsight bias when backtesting?
Use bar replay so future candles stay hidden, decide each trade before you step forward, and log every setup, wins and losses alike.
Does hindsight bias affect how I judge losses?
Yes. It makes good decisions that lost look like mistakes. Judge the trade by whether you followed the plan. See process vs outcome.
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