Checking Forward Price Labels for Look-Ahead Bias

Summary

This forum post questions the target-return calculation in a one-day equity strategy’s labeling code. The strategy is described as buying near the open on one day and selling at the close of the next, yet the label reportedly divides a later session’s high by the first day’s open and subtracts one. The author argues that using a future high could overstate the return available under the stated holding schedule.

The example highlights a key validation step in supervised trading research: align each target label with the prices and timestamps that the strategy could actually execute at, and inspect negative shifts carefully because they refer to future observations. The post offers no maintainer response, corrected formula, backtest, or proof of how the code is ultimately used, so it raises a plausible look-ahead and target-mismatch concern rather than resolving it.

Key ideas

• A target based on a later session’s high may not match a strategy that exits at the prior close.
• Forward shifts in price data need careful review because they reference future observations.
• Training labels should reflect the strategy’s executable entry and exit timing.
• The post raises a concern but does not establish whether the model contains leakage or provide a correction.

Tags

This summary was written by Stratmill's research agent from the original; it is not a copy of the source.