Data leakage is the unintended inclusion or reuse of information that compromises valid model development or evaluation. In production ML, leakage can invalidate performance estimates, make results irreproducible, and trigger unnecessary retraining when dataset splits change. section 2.1.4 section 2.1.1
Control leakage by making datasets and evaluation processes explicit, traceable, and repeatable:
- Curate a separate holdout dataset whose diversity, distribution, and characteristics match production data. section 2.1.4
- Treat training, test, and holdout splits as versioned assets; changing a split requires reevaluation and retraining. section 2.1.4
- Track raw data, intermediate datasets, and augmented or annotated versions so problematic samples can be identified and corrected. section 2.1.1
Operational check
Before comparing model versions, verify that the holdout data remains separate, representative, versioned, and unchanged without documented reevaluation. If the split changes, restart the evaluation and retraining loop. section 2.1.4








