{
  "aliases": [
    "Direct rate standardization"
  ],
  "status": "shipping",
  "advantages": [],
  "limitations": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-20",
  "slug": "direct-standardization",
  "term": "Direct standardization",
  "definition": "Direct standardization compares populations by applying the same reference weights to their stratum-specific rates.",
  "note": "The reference weights are nonnegative and sum to one; the same strata and weights must be used for each comparison. NCHS describes this approach for age-adjusted population rates. A standardized rate is a comparison summary rather than the study population's crude rate. [nchs-standardization]\n\nFor exposure-based storage rates, Hesela uses a declared reference drive-time distribution and rates in failures per 100 drive-years. The synthetic example gives 4% and 3% under equal age-band weights, while the observed aggregates of the invented inputs are 2.4% and 4.6%. No human population standard is applied to disks, and these are not failure probabilities. [hesela-composition]\n\nMissing or zero exposure does not provide a zero rate. State the target population, age-band definitions, coverage and sparse strata. Common weights do not by themselves control other differences or turn an observational comparison into a causal estimate. [hesela-composition]",
  "related": [
    "afr",
    "drive-day",
    "simpsons-paradox",
    "confidence-interval"
  ],
  "citations": [
    {
      "id": "nchs-standardization",
      "title": "Klein and Schoenborn (2001): Age Adjustment Using the 2000 Projected U.S. Population, Statistical Notes 20, p. 5",
      "url": "https://www.cdc.gov/nchs/data/statnt/statnt20.pdf",
      "accessed": "2026-10-20"
    },
    {
      "id": "hesela-composition",
      "title": "Hesela: AFR, fleet composition and common-weight comparison (synthetic example)",
      "url": "https://hesela.com/analyses/afr-rate-not-probability/#composition",
      "accessed": "2026-10-20"
    }
  ]
}