Lookahead bias
Lookahead bias is the use of information in a backtest that was not available at the moment the trade would have been taken.
How it works
In Pine Script the common source is a higher-timeframe request with lookahead enabled, which hands each historical bar the completed higher-timeframe value before it existed. Other sources include indicators that centre their calculation window, pivot functions that confirm several bars later, and any reference to a future bar index. The result is a backtest that is not merely optimistic but structurally impossible.
Why it matters on a funded account
Lookahead is harder to spot than repainting because the chart looks stable on reload. The test is whether every input to a signal was knowable at the signal's timestamp.
Read next
Part of the Puravida Edge prop trading glossary. Firm-specific figures verified September 2026; rules change frequently — confirm on the firm's site.
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