{
  "alt": "Two small line charts of the gap between an end bracket and the pooled middle three brackets in five presidential elections, each with a confidence band and a line at zero. The highest-minus-middle gap rises from {fact:rm_2008} in 2008 to {fact:rm_2016} in 2016 and {fact:rm_2024} in 2024. The lowest-minus-middle gap falls from {fact:pm_2008} in 2008 to {fact:pm_2024} in 2024 and stays above zero.",
  "caption": "In 2024 both ends of the income range are above the middle three brackets, the highest by {fact:rm_2024} points and the lowest by {fact:pm_2024}. The highest bracket's edge rose from {fact:rm_2008} points in 2008, an interval that includes zero, while the lowest bracket's edge fell and stayed above zero. Each panel is one contrast, the Democratic share of the first group minus that of the pooled middle three, and a value above the dashed line at zero means the first group is more Democratic. Bands are confidence intervals.",
  "data": [
    {
      "cl_high": 3.9236,
      "cl_low": -1.34008,
      "conf_high": 4.2834,
      "conf_low": -1.69988,
      "contrast": "Highest bracket minus the middle three",
      "estimate": 1.29176,
      "n": 18311,
      "year": 2008
    },
    {
      "cl_high": 7.3831,
      "cl_low": 0.211686,
      "conf_high": 7.02109,
      "conf_low": 0.573704,
      "contrast": "Highest bracket minus the middle three",
      "estimate": 3.7974,
      "n": 26151,
      "year": 2012
    },
    {
      "cl_high": 10.6837,
      "cl_low": 5.62352,
      "conf_high": 10.5329,
      "conf_low": 5.77436,
      "contrast": "Highest bracket minus the middle three",
      "estimate": 8.15363,
      "n": 29547,
      "year": 2016
    },
    {
      "cl_high": 10.1905,
      "cl_low": 5.19243,
      "conf_high": 9.63305,
      "conf_low": 5.7499,
      "contrast": "Highest bracket minus the middle three",
      "estimate": 7.69148,
      "n": 31787,
      "year": 2020
    },
    {
      "cl_high": 12.4447,
      "cl_low": 6.86792,
      "conf_high": 11.7924,
      "conf_low": 7.52019,
      "contrast": "Highest bracket minus the middle three",
      "estimate": 9.65631,
      "n": 31144,
      "year": 2024
    },
    {
      "cl_high": 12.4704,
      "cl_low": 8.3991,
      "conf_high": 12.5797,
      "conf_low": 8.28975,
      "contrast": "Lowest bracket minus the middle three",
      "estimate": 10.4347,
      "n": 20577,
      "year": 2008
    },
    {
      "cl_high": 9.73217,
      "cl_low": 4.71293,
      "conf_high": 9.20307,
      "conf_low": 5.24202,
      "contrast": "Lowest bracket minus the middle three",
      "estimate": 7.22255,
      "n": 30817,
      "year": 2012
    },
    {
      "cl_high": 6.92924,
      "cl_low": 2.649,
      "conf_high": 6.66297,
      "conf_low": 2.91527,
      "contrast": "Lowest bracket minus the middle three",
      "estimate": 4.78912,
      "n": 33833,
      "year": 2016
    },
    {
      "cl_high": 7.08031,
      "cl_low": 3.0584,
      "conf_high": 6.83901,
      "conf_low": 3.29969,
      "contrast": "Lowest bracket minus the middle three",
      "estimate": 5.06935,
      "n": 35746,
      "year": 2020
    },
    {
      "cl_high": 7.04389,
      "cl_low": 0.912081,
      "conf_high": 6.28204,
      "conf_low": 1.67393,
      "contrast": "Lowest bracket minus the middle three",
      "estimate": 3.97799,
      "n": 33761,
      "year": 2024
    }
  ],
  "id": "gap_contrasts",
  "notes": [
    "Brackets are in the nominal dollars of each survey year; the lowest and highest brackets hold a different share of voters in different years.",
    "Intervals are model based (Kish effective sample size, normal approximation) and ignore clustering in the sample design.",
    "The bands use the Kish effective sample size. The last two columns of the table give intervals from standard errors clustered by state, which are wider."
  ],
  "source": "Cooperative Election Study cumulative file, presidential years 2008, 2012, 2016, 2020 and 2024; weighted (weight_cumulative); two-party presidential voters who reported household income",
  "spec": {
    "annotations": [
      {
        "label": "No difference",
        "type": "y-rule",
        "y": 0
      }
    ],
    "endLabels": false,
    "facet": "contrast",
    "facetColumns": 1,
    "hi": "conf_high",
    "lo": "conf_low",
    "n": "n",
    "x": "year",
    "xDomain": [
      2008,
      2024
    ],
    "xLabel": "Presidential election year",
    "y": "estimate",
    "yDomain": [
      -5,
      15
    ],
    "yFormat": {
      "digits": 0
    },
    "yLabel": "Difference in Democratic share (percentage points)"
  },
  "subtitle": "Difference in the Democratic share of the two-party presidential vote between an end bracket and the pooled middle three brackets, percentage points, by presidential election; two-party voters who reported income; 95% intervals from the Kish effective sample size",
  "table": {
    "columns": [
      {
        "key": "contrast",
        "label": "Contrast"
      },
      {
        "key": "year",
        "label": "Election"
      },
      {
        "format": {
          "digits": 1,
          "signed": true
        },
        "key": "estimate",
        "label": "Difference (points)"
      },
      {
        "format": {
          "digits": 1
        },
        "key": "conf_low",
        "label": "95% CI low (Kish)"
      },
      {
        "format": {
          "digits": 1
        },
        "key": "conf_high",
        "label": "95% CI high (Kish)"
      },
      {
        "format": {
          "digits": 1
        },
        "key": "cl_low",
        "label": "95% CI low (clustered by state)"
      },
      {
        "format": {
          "digits": 1
        },
        "key": "cl_high",
        "label": "95% CI high (clustered by state)"
      },
      {
        "key": "n",
        "label": "n voters"
      }
    ]
  },
  "title": "The highest bracket's edge over the middle three rose from {fact:rm_2008} to {fact:rm_2024} points, while the lowest bracket's fell from {fact:pm_2008} to {fact:pm_2024}",
  "type": "line",
  "width": "wide"
}