{
  "schema": "vedokrok.public-item.v1",
  "release_id": "MHC-RPUB-20260920-75ad787a",
  "url": "/knowledge/read-a-percentile-as-a-rank-not-a-score",
  "id": "MHC-D-RESEARCH-0249",
  "version": "0.1.0",
  "title": "Read a percentile as a rank, not a score",
  "summary": "The 90th percentile is a position in a crowd, not ninety correct answers out of a hundred.",
  "kind": "concept",
  "body": "Identify the reference group, the measured quantity and the direction that matters. A percentile locates a value within ordered observations. A high percentile can be desirable for a score and undesirable for a waiting time.",
  "limits": [
    "Sample size, ties and calculation conventions affect exact values; a historical percentile is not a guarantee."
  ],
  "topics": [
    "union-numerical-reasoning"
  ],
  "intents": [],
  "source_ids": [
    "RS-81EEEF7FC90B7C41"
  ],
  "evidence": [
    {
      "claim": "A percentile describes a position in an ordered distribution, not the percentage of a task that someone completed correctly.",
      "source_id": "RS-81EEEF7FC90B7C41",
      "role": "supports",
      "note": "Ties, small samples and software conventions can affect exact percentile calculations.",
      "locator": "Percentile definitions and interpretation"
    }
  ],
  "use_when": [
    "A test, service report or benchmark presents a percentile."
  ],
  "avoid_when": [
    "Sample size, ties and calculation conventions affect exact values; a historical percentile is not a guarantee."
  ],
  "example": "A reported 90th-percentile waiting time is a tail threshold, not the maximum wait or a promise to every future customer.",
  "check": "You can translate the percentile into a sentence about the distribution it summarizes.",
  "sources": [
    {
      "id": "RS-81EEEF7FC90B7C41",
      "title": "Introductory Statistics 2e, 2.3: Measures of the Location of the Data",
      "url": "https://openstax.org/books/introductory-statistics-2e/pages/2-3-measures-of-the-location-of-the-data"
    }
  ],
  "relations": [
    {
      "from": "MHC-D-RESEARCH-0249",
      "to": "MHC-D-RESEARCH-0250",
      "type": "useful_with",
      "url": "/knowledge/put-variation-beside-the-average"
    }
  ],
  "collections": [
    {
      "id": "RC-D976097B2A42D9AC",
      "title": "Make the numbers answer the right question",
      "url": "/collections/make-the-numbers-answer-the-right-question"
    }
  ]
}