{
  "id": "nagareyama-child-cohort-hybrid",
  "version": "nagareyama-child-cohort-hybrid-v1.0.0",
  "title": "流山市ローカル・コーホート／社人研リベース・ハイブリッド",
  "trainedThrough": "2026-04-01",
  "forecastThrough": "2032-04-01",
  "updatedAt": "2026-07-15",
  "inputSourceIds": [
    "nagareyama-town-single-age-population",
    "ipss-municipal-projection-2023",
    "ipss-municipal-births-2025",
    "ipss-survival-rates-2023",
    "ipss-net-migration-rates-2023",
    "ipss-child-woman-ratio-2023"
  ],
  "parameters": {
    "cohortRatioWindowYears": 10,
    "winsorLowerPercentile": 10,
    "winsorUpperPercentile": 90,
    "backtestFirstOrigin": 2015,
    "backtestLastOrigin": 2020,
    "maxBacktestHorizonYears": 6,
    "ageZeroSelectedModels": "persistence,birth_projection",
    "ageZeroWeights": "persistence:0.502985,birth_projection:0.497015",
    "hybridWeights": "{\"0_14\": {\"ipss\": 0.23507642098572076, \"ipssMae\": 3576.1466426170773, \"local\": 0.7649235790142791, \"localMae\": 1099.0218849703297}, \"0_2\": {\"ipss\": 0.3998036281856433, \"ipssMae\": 697.7305026000578, \"local\": 0.6001963718143567, \"localMae\": 464.7731967989596}, \"12_14\": {\"ipss\": 0.2307978462576258, \"ipssMae\": 185.22253920512878, \"local\": 0.7692021537423741, \"localMae\": 55.57571948924902}, \"3_5\": {\"ipss\": 0.26628160481226376, \"ipssMae\": 915.3512541411908, \"local\": 0.7337183951877363, \"localMae\": 332.19993190612126}, \"6_11\": {\"ipss\": 0.11927991544571093, \"ipssMae\": 1881.7239506723502, \"local\": 0.8807200845542892, \"localMae\": 254.85040896047764}}",
    "intervalMethod": "rolling-backtest signed residual p10/p90 by single age and horizon"
  },
  "backtest": {
    "mae1Year": 423.478,
    "mape1Year": 1.5,
    "mae3Year": 1290.927,
    "mape3Year": 4.2261,
    "mae6Year": 2214.025,
    "mape6Year": 6.6243
  },
  "limitations": [
    "4月1日住民基本台帳人口の市全体モデルであり、町丁字別の転入開発は直接モデル化していない。",
    "社人研の公式値は10月1日基準であり、増減率だけを4月1日実績へリベースした。",
    "0歳は在住0歳人口であり、年間出生数と一致しない。",
    "2030～2032年のサービス需要は市公式値ではなく、人口推計と2025～2029年需要率からの派生値である。"
  ],
  "sourceId": "nagareyama-town-single-age-population",
  "forecastKind": "site_estimate",
  "universe": "resident_population",
  "basisDate": "毎年4月1日",
  "retrievedAt": "2026-07-15",
  "methodVersion": "nagareyama-child-cohort-hybrid-v1.0.0",
  "qualityFlags": [
    "site_model_configuration"
  ]
}