Public data model
Owned by tunes. tunes-web produces candidates; releases are versioned artefacts of this programme.
Layers (keep separate)
| Layer | Contents | Mutability |
|---|---|---|
| L0 Contribution records | Derived metrics per section, flags, device/app versions, consent class | Immutable once released; corrections via superseding records |
| L1 Derived reprocess | Same inputs, new algorithm version | New dataset version, never silent overwrite |
| L2 Aggregates | Section summaries, ranges, sample counts, tier mix, time-of-day slices | Regenerable from L0/L1 with version pin |
| L3 Interpretations | Passenger-facing copy, map styles, “quieter” rankings | Explicitly labelled as interpretation; not raw science |
Objective metrics and subjective perception stay in separate fields and should not be fused into one unexplained public score.
Required provenance fields (minimum)
- schema_version, processing_pipeline_version
- network_profile_id (e.g. london-underground@date)
- section_id, direction, duration_T
- metrics with weighting (never mix A/C/peak into one field)
- device_model, os_version, app_version
- calibration_state / tier
- quality_flags[]
- uncertainty / confidence dimensions present or explicitly null
- contribution_pseudonym or equivalent withdrawal handle (not public identity)
Release package
- Machine-readable export (e.g. Parquet/JSON Lines) + data dictionary
- Checksums, changelog, licence, citation snippet
- Methodology pointer (docs in
tunes)
Map honesty contract
Public map layers must expose sample size, uncertainty, tier distribution, and caveats. Sparse sections must not be ranked as if precise.
Recommendation
Publish L2 for the first public map; offer L0/L1 to researchers under the same open licence once anonymisation review passes.
Confidence: Medium until schema freeze (Phase 1).
Depends on experiment/legal/user-test? Legal for anonymisation; pilot for aggregate stability.
Links: ../research/10-open-data-reproducibility.md; data-flow-and-privacy-boundaries.md; H13 public map; H16 schema; [data-contracts.md](../../../../tunes-web/docs/tunes/data-contracts.md).