I have a categorical variable x1 with four levels(a, b, c and d). I run a few tests and find that one of those levels(say d) does not contribute much towards predicting the target variable.
Now is it possible for me to include just the first three categories of x1 to predict my target variable?
I read that for linear regression, reference coding is used and removing one level from a predictor variable would change the coding of the other levels. Here’s a link to the article:
And is this the same case with tree based methods too?
Thank you for the answer!!