{
  "snapshot_date": "2026-07-28",
  "question": "How much of the spread in Canadian child-welfare in-care rates is the age span of the denominator rather than the care system?",
  "method": "Narrow each jurisdiction to a common 0-17 denominator while keeping its whole numerator. This is an UPPER BOUND, not a correction: every child aged 18 or over genuinely in a count stays in its numerator, because no jurisdiction publishes in-care counts by age. The true standardised rate lies between the published figure and the bound.",
  "sources": {
    "care": {
      "publisher": "Canadian Child Welfare Research Portal (CWRP), McGill University",
      "cite": "Pollock et al., 2024",
      "reference_year": "fiscal 2021/2022",
      "url": "https://cwrp.ca/statistics-matrix",
      "archived_file": "data/raw/cwrp/statistics-matrix.html",
      "sha256": "088f2a9aad5cf54ff68ca0dad097b6a0ed71b2772ad873faba91f44bdd78bcf8",
      "bytes": 30953
    },
    "population": {
      "publisher": "Statistics Canada",
      "table": "17-10-0005-01, population estimates on July 1 by age and gender",
      "vintage": "2021",
      "vintage_chosen_by": "tested 2019 to 2023 against CWRP's own published denominator for Nova Scotia; 2021 matched at 0.75%, 2022 at 2.96%. Not assumed from the page's stated year.",
      "archived_file": "data/raw/statcan/17100005/17100005-eng.zip",
      "basis": "single years of age only; age bands excluded so they cannot be summed with single years"
    }
  },
  "findings": {
    "spread_published": 10.88,
    "spread_at_bound": 11.1,
    "spread_is_explained_by_age_span": false,
    "spread_note": "Both extremes, Manitoba and Ontario, already count to 0-17, so the headline spread survives standardisation almost unchanged. The age span does not explain it.",
    "ranking_is_stable": false,
    "ranking_note": "Yukon rises three places, Nunavut and Northwest Territories each fall two while their own rates rise. Ordering jurisdictions on these rates orders them partly by legislative drafting.",
    "control_jurisdictions_0_17": [
      "Alberta",
      "Manitoba",
      "Ontario",
      "Quebec",
      "Prince Edward Island"
    ],
    "noise_floor_pct": 1.48,
    "noise_floor_note": "Jurisdictions already counting to 17 should show zero change; what they do show is the StatCan revision noise. A change inside this floor is not a finding.",
    "above_noise_floor": [
      "Yukon 0-25 +48.26%",
      "Newfoundland and Labrador 0-21 +26.75%",
      "Saskatchewan 0-21 +23.12%",
      "Nova Scotia 0-20 +17.75%",
      "New Brunswick 0-18 +6.34%",
      "Northwest Territories 0-18 +5.73%",
      "British Columbia 0-18 +4.01%",
      "Nunavut 0-18 +2.97%"
    ]
  },
  "jurisdictions": [
    {
      "jurisdiction": "British Columbia",
      "age_span": "0-18",
      "children_in_care": 10462,
      "child_population_published": 926027,
      "rate_per_1000_published": 11.3,
      "published_rate_reconciles": true,
      "population_0_17_statcan": 890147,
      "upper_bound_per_1000_on_0_17": 11.7531,
      "change_pct": 4.01,
      "rank_published": 8,
      "rank_at_bound": 8,
      "rank_change": 0
    },
    {
      "jurisdiction": "Alberta",
      "age_span": "0-17",
      "children_in_care": 8164,
      "child_population_published": 973725,
      "rate_per_1000_published": 8.38,
      "published_rate_reconciles": true,
      "population_0_17_statcan": 979897,
      "upper_bound_per_1000_on_0_17": 8.3315,
      "change_pct": -0.58,
      "rank_published": 10,
      "rank_at_bound": 10,
      "rank_change": 0
    },
    {
      "jurisdiction": "Saskatchewan",
      "age_span": "0-21",
      "children_in_care": 5719,
      "child_population_published": 331213,
      "rate_per_1000_published": 17.27,
      "published_rate_reconciles": true,
      "population_0_17_statcan": 268969,
      "upper_bound_per_1000_on_0_17": 21.2627,
      "change_pct": 23.12,
      "rank_published": 4,
      "rank_at_bound": 3,
      "rank_change": 1
    },
    {
      "jurisdiction": "Manitoba",
      "age_span": "0-17",
      "children_in_care": 9196,
      "child_population_published": 310705,
      "rate_per_1000_published": 29.6,
      "published_rate_reconciles": true,
      "population_0_17_statcan": 309210,
      "upper_bound_per_1000_on_0_17": 29.7403,
      "change_pct": 0.47,
      "rank_published": 1,
      "rank_at_bound": 1,
      "rank_change": 0
    },
    {
      "jurisdiction": "Ontario",
      "age_span": "0-17",
      "children_in_care": 7489,
      "child_population_published": 2750014,
      "rate_per_1000_published": 2.72,
      "published_rate_reconciles": true,
      "population_0_17_statcan": 2794389,
      "upper_bound_per_1000_on_0_17": 2.68,
      "change_pct": -1.47,
      "rank_published": 13,
      "rank_at_bound": 13,
      "rank_change": 0
    },
    {
      "jurisdiction": "Quebec",
      "age_span": "0-17",
      "children_in_care": 15201,
      "child_population_published": 1604195,
      "rate_per_1000_published": 9.48,
      "published_rate_reconciles": true,
      "population_0_17_statcan": 1621661,
      "upper_bound_per_1000_on_0_17": 9.3737,
      "change_pct": -1.12,
      "rank_published": 9,
      "rank_at_bound": 9,
      "rank_change": 0
    },
    {
      "jurisdiction": "New Brunswick",
      "age_span": "0-18",
      "children_in_care": 1083,
      "child_population_published": 143925,
      "rate_per_1000_published": 7.52,
      "published_rate_reconciles": true,
      "population_0_17_statcan": 135429,
      "upper_bound_per_1000_on_0_17": 7.9968,
      "change_pct": 6.34,
      "rank_published": 11,
      "rank_at_bound": 11,
      "rank_change": 0
    },
    {
      "jurisdiction": "Nova Scotia",
      "age_span": "0-20",
      "children_in_care": 1180,
      "child_population_published": 197359,
      "rate_per_1000_published": 5.98,
      "published_rate_reconciles": true,
      "population_0_17_statcan": 167575,
      "upper_bound_per_1000_on_0_17": 7.0416,
      "change_pct": 17.75,
      "rank_published": 12,
      "rank_at_bound": 12,
      "rank_change": 0
    },
    {
      "jurisdiction": "Prince Edward Island",
      "age_span": "0-17",
      "children_in_care": 387,
      "child_population_published": 29995,
      "rate_per_1000_published": 12.9,
      "published_rate_reconciles": true,
      "population_0_17_statcan": 29563,
      "upper_bound_per_1000_on_0_17": 13.0907,
      "change_pct": 1.48,
      "rank_published": 7,
      "rank_at_bound": 7,
      "rank_change": 0
    },
    {
      "jurisdiction": "Newfoundland and Labrador",
      "age_span": "0-21",
      "children_in_care": 1495,
      "child_population_published": 106836,
      "rate_per_1000_published": 13.99,
      "published_rate_reconciles": true,
      "population_0_17_statcan": 84311,
      "upper_bound_per_1000_on_0_17": 17.732,
      "change_pct": 26.75,
      "rank_published": 6,
      "rank_at_bound": 6,
      "rank_change": 0
    },
    {
      "jurisdiction": "Yukon",
      "age_span": "0-25",
      "children_in_care": 205,
      "child_population_published": 12433,
      "rate_per_1000_published": 16.49,
      "published_rate_reconciles": true,
      "population_0_17_statcan": 8385,
      "upper_bound_per_1000_on_0_17": 24.4484,
      "change_pct": 48.26,
      "rank_published": 5,
      "rank_at_bound": 2,
      "rank_change": 3
    },
    {
      "jurisdiction": "Northwest Territories",
      "age_span": "0-18",
      "children_in_care": 218,
      "child_population_published": 11228,
      "rate_per_1000_published": 19.42,
      "published_rate_reconciles": true,
      "population_0_17_statcan": 10617,
      "upper_bound_per_1000_on_0_17": 20.5331,
      "change_pct": 5.73,
      "rank_published": 3,
      "rank_at_bound": 5,
      "rank_change": -2
    },
    {
      "jurisdiction": "Nunavut",
      "age_span": "0-18",
      "children_in_care": 305,
      "child_population_published": 15208,
      "rate_per_1000_published": 20.06,
      "published_rate_reconciles": true,
      "population_0_17_statcan": 14766,
      "upper_bound_per_1000_on_0_17": 20.6556,
      "change_pct": 2.97,
      "rank_published": 2,
      "rank_at_bound": 4,
      "rank_change": -2
    }
  ]
}