Define the claim behind the split
A random document split may answer whether a system handles more examples of familiar templates. It may not answer whether it handles unseen customers or future templates. State which claim matters commercially. Group-aware and time-aware evaluation can make that distinction visible when used with an appropriate task design.
Build a small manifest
Record a stable record ID, source group, template family, time, segment, split and synthetic provenance. Avoid uploading raw customer documents to this demo. The local inspector checks exact identifiers, group crossings, exact sanitised text matches and a declared temporal rule. It also checks whether required production segments appear in the holdout.
Interpret findings carefully
A group crossing is a reason to inspect the split, not automatic proof that every evaluation is invalid. Its significance depends on the intended generalisation claim. Exact text overlap is stronger evidence of repetition but still requires context. A clean metadata report does not establish the absence of paraphrases or semantic duplicates.
Repair the evaluation before reporting uplift
Quarantine contaminated families and rebuild partitions under a recorded policy. Re-run the dated baseline and candidate on the new protected data. Do not retain the old headline score as if the test were unchanged. Keep an evidence register showing what was inspected, the decision taken and the limitations that remain.
Bring to the decision review
Keep the original manifest, the finding register and the revised allocation side by side. Mark which groups were removed or reassigned and explain how this changes the interpretation of previous results. Store stable hashes or identifiers for the approved evaluation material in your real evidence system. This browser tool does not establish access controls over a holdout or prevent an experimenter from seeing its contents.
Sources & editorial record
This is Frontier Development’s decision framework. The references below support the general technical concepts; the worked scenarios and procurement questions are our analysis.
- scikit-learn · Grouped cross-validation · checked 16 October 2026 ↗
- Cross-validation and grouped splits — scikit-learn ↗
References accessed 16 October 2026. No current price, product availability or legal clearance is asserted. Published study findings are attributed above; this guide reports no Frontier Development experiment. Read the comparison method.
Review history and research boundary
Edition 1.1 · 16 October 2026: added claim-level attribution, explicit evidence boundaries and links to the flagship synthesis. Published by Frontier Development. No named external technical reviewer is recorded. This guide provides a decision framework; it is not a Frontier Development experimental result.
Read the primary-study synthesis →Open the leakage tool
Explore a complete synthetic example before using your own inputs.