{
  "id": "1997-april-correction",
  "slug": "1997-april-correction",
  "url": "https://dwillis.github.io/uplink/article/1997-april-correction.html",
  "year": 1997,
  "month": "April",
  "monthNum": 4,
  "headline": "Correction",
  "kicker": "",
  "author_name": "",
  "author_title": "",
  "affiliation": "",
  "summary": "A correction is provided for the Gini coefficient formula used in February's lead story, detailing the proper mathematical calculation with cumulative proportions of households and income.",
  "keywords": [
    "Gini",
    "formula",
    "correction"
  ],
  "topics": [
    "Data & Databases"
  ],
  "technologies": [],
  "full_text": "There was an error in the formula for February's lead story about the Gini coefficient.\n\nThe correct formula is:\n\nGini coefficient=1 - SUM ( (Xi-Xj) * (Yi+Yj))\n\nwhere:\nX is the cumulative proportion of households;\nY is the cumulative proportion of income;\ni is a particular income category;\nj is i-1, or the preceding income category.\n*Xi, Xj, Yi, Yj must equal one or less",
  "provenance": {
    "extracted_by": "anthropic/claude-sonnet-4-6",
    "extracted_at": "2026-07-05",
    "verified": true
  },
  "similar": [
    {
      "slug": "1992-september-correction",
      "score": 0.313
    },
    {
      "slug": "1992-june-correction",
      "score": 0.305
    },
    {
      "slug": "1997-february-to-have-or-to-have-not",
      "score": 0.295
    },
    {
      "slug": "1991-july-uplink-correction",
      "score": 0.253
    },
    {
      "slug": "1998-september-stats-from-the-road",
      "score": 0.217
    }
  ],
  "html_url": "https://dwillis.github.io/uplink/article/1997-april-correction.html",
  "json_url": "https://dwillis.github.io/uplink/article/1997-april-correction.json"
}