{
  "version": 1,
  "kind": "venn",
  "title": "Bird species recorded at four ponds",
  "sets": [
    {
      "id": "a",
      "text": "Mill pond"
    },
    {
      "id": "b",
      "text": "Church pond"
    },
    {
      "id": "c",
      "text": "Quarry lake"
    },
    {
      "id": "d",
      "text": "Marsh pool"
    }
  ],
  "regions": [
    {
      "in": [
        "a"
      ],
      "text": "12"
    },
    {
      "in": [
        "b"
      ],
      "text": "7"
    },
    {
      "in": [
        "c"
      ],
      "text": "9"
    },
    {
      "in": [
        "d"
      ],
      "text": "15"
    },
    {
      "in": [
        "a",
        "b"
      ],
      "text": "4"
    },
    {
      "in": [
        "a",
        "c"
      ],
      "text": "3"
    },
    {
      "in": [
        "a",
        "d"
      ],
      "text": "2"
    },
    {
      "in": [
        "b",
        "c"
      ],
      "text": "5"
    },
    {
      "in": [
        "b",
        "d"
      ],
      "text": "1"
    },
    {
      "in": [
        "c",
        "d"
      ],
      "text": "6"
    },
    {
      "in": [
        "a",
        "b",
        "c"
      ],
      "text": "3"
    },
    {
      "in": [
        "a",
        "b",
        "d"
      ],
      "text": "2"
    },
    {
      "in": [
        "a",
        "c",
        "d"
      ],
      "text": "1"
    },
    {
      "in": [
        "b",
        "c",
        "d"
      ],
      "text": "4"
    },
    {
      "in": [
        "a",
        "b",
        "c",
        "d"
      ],
      "text": "**21**",
      "role": "emphasis"
    }
  ],
  "caption": "Species seen at each combination of ponds over one spring survey; 21 were seen at all four."
}