How to construct a regression tree

Hi,

As I was trying to understand the matlab example on the documentation page for constructing a regression tree https://uk.mathworks.com/help/stats/regressiontree-class.html, below is the example.

>> load carsmall;
>> whos
  Name                Size            Bytes  Class     Attributes
  Acceleration      100x1               800  double              
  Cylinders         100x1               800  double              
  Displacement      100x1               800  double              
  Horsepower        100x1               800  double              
  MPG               100x1               800  double              
  Mfg               100x13             2600  char                
  Model             100x33             6600  char                
  Model_Year        100x1               800  double              
  Origin            100x7              1400  char                
  Weight            100x1               800  double   
  
  >> tree = fitrtree([Weight, Cylinders],MPG,...
                'categoricalpredictors',2,'MinParentSize',20,...
                'PredictorNames',{'W','C'})
tree = 
  RegressionTree
           PredictorNames: {'W'  'C'}
             ResponseName: 'Y'
    CategoricalPredictors: 2
        ResponseTransform: 'none'
          NumObservations: 94
  Properties, Methods
  
  >> mileage4K = predict(tree,[4000 4; 4000 6; 4000 8])
mileage4K =
   19.2778
   19.2778
   14.3889

I wonder how the mileage is predicted while there is no variable in 'carsmall' named mileage.

[Star Strider]

MPG               100x1               800  double 

The documentation states for the ‘mileage4k’ assignment:

‘Predict the mileage of 4,000-pound cars with 4, 6, and 8 cylinders.’

In U.S. usage at least, ‘MPG’ stands for ‘miles per gallon’. That can be considered ‘mileage’. At least that would be my guess.

[Salad Box]

Yes you are right. Someone who constructed 'fitrtree' documentation webpage has comfirmed that the varialbe 'MPG' is the variable 'mileage'. But as someone living in the UK, mileage means the total miles a car has been driven.

Thanks for answering!

[Star Strider]

My pleasure!

As Winston Churchill noted, the U.S. and the U.K. are ‘two nations divided by a common language’.