Data sources & provenance

Every size recommendation carries provenance: where the number came from, when it was last verified, and how confident we are. We cite sources, triangulate conflicts, and avoid copying competitor charts.

Source types

official_chart. Published brand size charts. We anchor on foot length in millimetres and store version dates.
lab_measure. Third-party lab measurements used as calibration anchors with attribution and URL.
review_aggregate. Aggregated buyer fit reports, such as runs small, true to size, or runs large, with sample size when available.
community_feedback. Anonymous first-party fit feedback. This becomes more valuable as volume grows.

What we do not do

Claim one exact brand-level size exists when real shoes vary by model and last.
Republish trademarked brand charts or logos inside embeddable widgets.
Index model pages without enough confidence and provenance.
Hide source disagreements. When charts conflict, we show the range.

Freshness

Each record stores a captured_date for last verification. We review top-brand data regularly and expand coverage as fit feedback accumulates.