{
  "alt": "Dot chart with three rows, one for each comparison, and two dots in each row for the ANES and the CES, with confidence intervals and a line at zero. In the CES the slope is {fact:three_ces_cross_section} for one decade older within an election, {fact:three_ces_same_age} for one decade later at the same age and {fact:three_ces_same_cohort} along a cohort. In the ANES the three slopes are {fact:three_anes_cross_section}, {fact:three_anes_same_age} and {fact:three_anes_same_cohort}.",
  "caption": "The three comparisons give different answers from the same voters: in the ANES the slopes are {fact:three_anes_cross_section}, {fact:three_anes_same_age} and {fact:three_anes_same_cohort}, and the third interval includes zero. The sum of the first two slopes minus the third is {fact:three_anes_sumdiff} in the ANES and {fact:three_ces_sumdiff} in the CES, with bootstrap intervals that exclude zero, and it would be zero if the three effects were straight lines. Each dot is a weighted regression coefficient and whiskers are 95% intervals.",
  "data": [
    {
      "comparison": "One decade older, same election (age and birth year)",
      "conf_high": -1.70031,
      "conf_low": -2.63982,
      "estimate": -2.17006,
      "n": 30571,
      "survey": "ANES 1952 to 2024"
    },
    {
      "comparison": "One decade older, same election (age and birth year)",
      "conf_high": -4.10111,
      "conf_low": -4.57891,
      "estimate": -4.34001,
      "n": 169858,
      "survey": "CES 2008 to 2024"
    },
    {
      "comparison": "One decade later, same age (election and birth year)",
      "conf_high": 1.91955,
      "conf_low": 1.33685,
      "estimate": 1.6282,
      "n": 30571,
      "survey": "ANES 1952 to 2024"
    },
    {
      "comparison": "One decade later, same age (election and birth year)",
      "conf_high": -0.538451,
      "conf_low": -1.79478,
      "estimate": -1.16661,
      "n": 169858,
      "survey": "CES 2008 to 2024"
    },
    {
      "comparison": "One decade later, same birth cohort (age and election)",
      "conf_high": 0.782186,
      "conf_low": -0.265221,
      "estimate": 0.258483,
      "n": 30571,
      "survey": "ANES 1952 to 2024"
    },
    {
      "comparison": "One decade later, same birth cohort (age and election)",
      "conf_high": -4.5533,
      "conf_low": -5.85383,
      "estimate": -5.20357,
      "n": 169858,
      "survey": "CES 2008 to 2024"
    }
  ],
  "id": "three_comparisons",
  "notes": [
    "Cross-section: weighted regression of the 0/1 Democratic vote on age in decades with a fixed effect for each election. Same age: regression on election year in decades with a fixed effect for each 4-year age band. Same cohort: regression on election year in decades with a fixed effect for each 4-year birth band. Voters aged 18 to 73 only, so the age and birth bands share one grid.",
    "The CES is an opt-in online panel, so its intervals describe sampling variation among panel members and leave out how respondents joined the panel."
  ],
  "source": "ANES Cumulative Data File, presidential elections 1952-2024; weighted (post-election weight where the file has one, otherwise VCF0009z); two-party presidential voters; CES Cumulative File, presidential elections 2008-2024; weighted (weight_cumulative); two-party presidential voters; weighted regression coefficients",
  "spec": {
    "colors": {
      "ANES 1952 to 2024": "cat1",
      "CES 2008 to 2024": "cat2"
    },
    "group": "survey",
    "hi": "conf_high",
    "lo": "conf_low",
    "n": "n",
    "reference": 0,
    "referenceLabel": "No change",
    "sort": "data",
    "x": "estimate",
    "xDomain": [
      -8,
      4
    ],
    "xFormat": {
      "digits": 1,
      "signed": true
    },
    "xLabel": "Change in the Democratic share (percentage points per decade)",
    "y": "comparison"
  },
  "subtitle": "Change in the Democratic share of the two-party vote per decade, three straight-line comparisons, voters aged 18 to 73, ANES 1952 to 2024 and CES 2008 to 2024; 95% intervals (HC3)",
  "table": {
    "columns": [
      {
        "key": "comparison",
        "label": "Comparison"
      },
      {
        "key": "survey",
        "label": "Survey"
      },
      {
        "format": {
          "digits": 1,
          "signed": true
        },
        "key": "estimate",
        "label": "Change (points per decade)"
      },
      {
        "format": {
          "digits": 1,
          "signed": true
        },
        "key": "conf_low",
        "label": "95% interval low"
      },
      {
        "format": {
          "digits": 1,
          "signed": true
        },
        "key": "conf_high",
        "label": "95% interval high"
      },
      {
        "format": {
          "thousands": true
        },
        "key": "n",
        "label": "Voters aged 18 to 73"
      }
    ]
  },
  "title": "In the CES the vote moved by {fact:three_ces_cross_section} points per decade of age within an election, {fact:three_ces_same_age} per decade at a fixed age and {fact:three_ces_same_cohort} along a cohort",
  "type": "dot",
  "width": "wide"
}