R - (Dummy Code|Categorical Variable) in Regression

C

• With a categorical predictor, dummy codes to represent the nominal variable as numeric using the function C (for contrasts)

myCategoricalPredictor <- C(data$CategoricalPredictor, treatment)
model <- lm(data$OutcomeVariable ~ data$NumericPredictorVariable + myCategoricalPredictor)

Contrast

contrasts will give you the details of the dummy variable.

contrasts(myObject)

Red    Blue
Green     0      0
Red       1      0
Blue      0      1