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Survivorship bias

QuantA dataset error where only assets that "survived" to the present are included, biasing the historical sample toward winners. Common in equity-index backtests.

Full definition

Survivorship bias arises when a historical dataset excludes assets that have since been delisted, merged, or gone bankrupt. The remaining sample is biased toward winners, which inflates backtest performance. On this site, gate G2 of the G1 to G31 evaluation stack requires every equity or index backtest to use a survivorship-bias-free universe (point-in-time constituent history) and to disclose the source.

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