{
  "aliases": null,
  "backlinks": [
    {
      "field": "defines",
      "target": "YB9390ZE4W"
    }
  ],
  "body": "\n## Summary\n\nFisher's exact test is a test of independence of two binary factors in a $2 \\times 2$ [[contingency table|PANSMHE0SW]].\nIt conditions on the row and column totals, and then the count in one cell has a [[hypergeometric distribution|0X3Y0ZSKNF]] under the null hypothesis.\nThe [[p-value|0GGKJGZF6D]] is computed exactly from this law, so the test is valid for small samples where the chi-squared approximation fails.\n\n## Explanations\n\n### L1 human\n\nRonald Fisher's lady tasting tea example illustrates the test.\nA lady claims she can tell whether milk or tea was poured first, and she gets $8$ cups, $4$ of each kind.\nIf she is guessing, the chance that she picks the right $4$ cups is $1/\\binom{8}{4} = 1/70$, about $0.014$.\nSo a fully correct answer is strong evidence against pure guessing.\n",
  "commit": "ff8a40749dc16545e3d2fc637f6b0196e81d0bfa",
  "front": {
    "kind": "concept",
    "msc": [
      "62H17",
      "62F03"
    ],
    "name": "Fisher's exact test",
    "same_as": {
      "wikidata": "Q41492",
      "wikipedia": "Fisher's exact test"
    },
    "sources": [
      {
        "url": "https://en.wikipedia.org/wiki/Fisher%27s_exact_test"
      }
    ],
    "specializes": [
      "087P03NEND"
    ],
    "tag": "J6JP5CJNPX"
  },
  "kind": "concept",
  "link": "https://tamnd.github.io/math2/node/J6JP5CJNPX/",
  "links": [
    {
      "field": "specializes",
      "target": "087P03NEND"
    }
  ],
  "markdown": "https://tamnd.github.io/math2/node/J6JP5CJNPX.md",
  "msc": [
    "62H17",
    "62F03"
  ],
  "name": "Fisher's exact test",
  "prov": null,
  "role": "",
  "source": "https://github.com/tamnd/math2/blob/main/nodes/J6J/J6JP5CJNPX.md",
  "status": null,
  "tag": "J6JP5CJNPX",
  "uri": "m2://J6JP5CJNPX",
  "url": "https://tamnd.github.io/math2/wiki/fishers-exact-test/",
  "writing": {
    "tag": "J6JP5CJNPX",
    "kind": "concept",
    "level": "W0",
    "next": [
      {
        "what": "an inventory row",
        "note": "the row of the inventory that the node accounts for",
        "have": 0,
        "want": 1
      },
      {
        "what": "a source with a locator",
        "have": 0,
        "want": 1
      }
    ]
  }
}