{
  "schema_version": 1,
  "release_date": "2026-09-13",
  "status": "research-release",
  "certification": "not externally certified",
  "cohort_calibration": {
    "publisher": "United Nations Department of Economic and Social Affairs, Population Division",
    "release": "World Population Prospects 2024, Online Edition",
    "source_file": "WPP2024_POP_F01_1_POPULATION_SINGLE_AGE_BOTH_SEXES.xlsx",
    "source_sha256": "78109efb998fee10bd0c501844e04cafd0922836239e00aa90d9f35fc828a94a",
    "method": "WPP mid-year single-age population divided by the model annual birth cohort, with linear interpolation between adjacent 1 July cohort factors",
    "coverage": {
      "canonical_entities": 237,
      "calibrated_entities": 236,
      "explicit_fallback_entities": ["Kosovo"]
    }
  },
  "birth_timing": {
    "seasonality": {
      "method": "Country monthly birth shares where published; M49 regional monthly profile otherwise; daily allocation within each month follows the disclosed calendar profile.",
      "source_tiers": [
        "Human Fertility Database Short-Term Fertility Fluctuations",
        "Eurostat demo_fmonth",
        "UN Demographic Yearbook monthly births",
        "Published country tables for nine additional countries"
      ],
      "provenance": "data/sources/seasonality/ and data/sources/seasonality/tier4/ in the model repository"
    },
    "hour_of_birth": {
      "source": "US CDC/NCHS Data Brief 200 table, with source record in the model repository",
      "scope": "A disclosed common hourly allocation curve; not country-specific vital-registration microdata."
    }
  },
  "independent_validation": {
    "sources": "US Census, Statistics Canada, Eurostat, UK ONS, Japan Statistics Bureau, and Australian Bureau of Statistics",
    "result": "51 country-year comparisons; median absolute percent error 2.35% after the per-year WPP calibration correction.",
    "artifact": "data/validation/model_vs_national.csv in the model repository"
  },
  "implementation": {
    "repository": "local source repository; public code mirror not yet declared",
    "revision": "65e9f9a"
  },
  "timezone_allocation": {
    "population_source": "GHS-POP R2023A, epoch 2025, global 1 km",
    "population_raster_sha256": "db9cdc20a7ab6d383f63b10b70929887fbd96200452cd48e4b6515c1a52b0f75",
    "timezone_boundaries": "Timezone Boundary Builder 2026c timezones-now",
    "timezone_geometry_sha256": "40471fed0621974b579e72ae3cfd68a9756c6c2894c348d738c6d6bec0139545",
    "method": "population-raster zonal sum at cell centres, normalized per canonical entity",
    "canonical_entities": 237,
    "single_zone_overrides": 9,
    "validation": "all 237 canonical entities have positive weights totaling exactly 100%"
  },
  "uncertainty": {
    "status": "not_published",
    "reason": "A sensitivity/model-spread interval has not yet passed validation. This release does not present one as a confidence interval."
  }
}