{
  "spec": {
    "data": {"url": "data/cars.json"},
    "mark": "?",
    "encodings": [
      {
        "channel": "x",
        "aggregate": "mean",
        "field": "Horsepower",
        "type": "quantitative"
      },{
        "channel": "y",
        "field": "Cylinders",
        "type": "ordinal"
      }
    ]
  },
  "chooseBy": "effectiveness"
}