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Data leakage

As explained in Machine Learning Platform Engineering

Data leakage is the unintended inclusion or reuse of information in a dataset that compromises valid model development or evaluation.

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

How Machine Learning Platform Engineering covers it

How deep it goes
Explains leakage through holdout curation, split changes, and sample-collection controls, but does not detail specific leakage algorithms.
Examples
Uses changing train-test-holdout splits and unintended sample leakage during data collection as operational examples.
What you can do after
Diagnose leakage by inspecting split changes, holdout integrity, dataset lineage, and sample provenance before evaluation.
How it connects
Connects data leakage with data lineage, dataset versioning, holdout datasets, model evaluation, and retraining.

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This explainer was generated by Manning's knowledge graph from the text of Machine Learning Platform Engineering. The section links point to the parts of the book it draws on.