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3.2.1 Understanding Probability Distributions

Code

Vega-Lite Chart

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  "description": "Comparison of Normal, Binomial, and Poisson Distributions",
  "hconcat": [
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      "width": 250,
      "height": 250,
      "title": "Normal Distribution",
      "data": {
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          "start": -4,
          "stop": 4,
          "step": 0.1,
          "as": "x"
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      },
      "transform": [
        {
          "calculate": "1 / (sqrt(2 * PI)) * exp(-0.5 * pow(datum.x, 2))",
          "as": "y"
        }
      ],
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          "mark": {
            "type": "line",
            "color": "blue"
          },
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              "field": "x",
              "type": "quantitative",
              "title": "Value"
            },
            "y": {
              "field": "y",
              "type": "quantitative",
              "title": "Probability Density"
            }
          }
        },
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            "type": "rule",
            "color": "red",
            "strokeDash": [
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              4
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          },
          "encoding": {
            "x": {
              "datum": 0
            }
          }
        },
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          "mark": {
            "type": "text",
            "align": "left",
            "dx": 5
          },
          "encoding": {
            "x": {
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            },
            "y": {
              "datum": 0.4
            },
            "text": {
              "value": "Mean, Median, Mode"
            }
          }
        }
      ]
    },
    {
      "width": 250,
      "height": 250,
      "title": "Binomial Distribution (n=10, p=0.5)",
      "data": {
        "sequence": {
          "start": 0,
          "stop": 10,
          "step": 1,
          "as": "k"
        }
      },
      "transform": [
        {
          "calculate": "pow(0.5, datum.k) * pow(0.5, 10-datum.k) * (factorial(10) / (factorial(datum.k) * factorial(10-datum.k)))",
          "as": "y"
        }
      ],
      "mark": "bar",
      "encoding": {
        "x": {
          "field": "k",
          "type": "ordinal",
          "title": "Number of Successes"
        },
        "y": {
          "field": "y",
          "type": "quantitative",
          "title": "Probability"
        }
      }
    },
    {
      "width": 250,
      "height": 250,
      "title": "Poisson Distribution (λ=5)",
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          "stop": 15,
          "step": 1,
          "as": "k"
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      },
      "transform": [
        {
          "calculate": "exp(-5) * pow(5, datum.k) / factorial(datum.k)",
          "as": "y"
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      ],
      "mark": "bar",
      "encoding": {
        "x": {
          "field": "k",
          "type": "ordinal",
          "title": "Number of Events"
        },
        "y": {
          "field": "y",
          "type": "quantitative",
          "title": "Probability"
        }
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