{
  "version": "phase4-v1",
  "date": "2026-10-11",
  "scope": "Descriptive authority screening and fixed LSOA feature support; partial completion of the original phase 4 gate",
  "originalProtocol": "../v1/protocol.json remains unchanged",
  "authorityBands": "A1–A10 are new outcome-free authority quantiles of the fixed road-weighted frost mean, over every frost-feature-eligible authority in the inherited 153-authority universe. Equal authority weights, nearest-rank cutpoints, ties retained. They are not the national LSOA D1–D10 bands.",
  "cohorts": "Primary: authorities screening-eligible in all five years. Sensitivity: all individually screening-eligible authority-years. Neither changes the frozen band reference population.",
  "periods": ["2021–2025 pooled", "2022–2025 pooled", "2021", "2022", "2023", "2024", "2025"],
  "geography": "England and all nine regions; no within-region recutting",
  "rurality": "Inherited ONS 2021 resident urban share: urban at least 80%, mixed 50% to below 80%, rural below 50%; these describe authorities, not miles on urban/rural roads. Unavailable context remains unknown.",
  "rates": "Sum eligible definite-motor collision counts / sum matched all-motor miles × 100000. Never average local rates or assign authority miles to LSOAs.",
  "uncertainty": "Exact 95% Garwood Poisson intervals conditional on fixed miles, plus 2000 percentile resamples of entire authorities retaining repeated years. Authority-resampling intervals displayed only with at least five authorities; cross-authority spatial dependence and exposure error remain outside these intervals.",
  "seed": 20261011,
  "minimumAuthoritiesForResampling": 5,
  "minimumCollisionsForSupport": 30,
  "context": "Exact authority/year joins to existing parking v4 source features only. No parking fitted results enter this analysis. Trunk share is road management mix, not major-road share. Elevation and detailed road-class mix are unavailable.",
  "tailDiagnostics": "For A9/A10 and LSOA D9/D10, report regional composition, actual frost range, geography count and concentration. For authorities also report mileage concentration and leave-largest-mileage-authority-out rate. Do not select merges or models from these results.",
  "lsoaSupport": "Fixed national D1–D10: LSOA counts, distinct shared climate-cell IDs, mapped road length and resident rurality composition. Climate-cell counts are not counts of independent observations. LSOA frequency and motor miles remain null.",
  "testYearDisclosure": "2025 appears in descriptive plots as requested by phase 4, so its frost association is now inspected. No model, control, merge or tuning decision is made; 2025 cannot subsequently be described as untouched. A future untouched year is required for prospective confirmation.",
  "claims": "Descriptive geographical association only. Incremental prediction and causality remain untested; all-road LSOA and matched major-road hypotheses remain unresolved."
}