Binning
Binning is the process of transforming a continuous variable into either a categorical variable or a set of discrete indicator variables.
Contents
Usage
In Regression Models
There is significant discussion surrounding the use of binning in regression models.
If the intention of binning is to capture non-linearity, then a non-linear model is generally preferable. Another common solution to that problem is to regress on a variable and the square of that variable.
Gelman discusses the approach partly in Regression and Other Stories and in blog posts: "One thing that people don't always realize is that you can do binning and linear together, for example in R, y ~ z + age + age.65.74 + age75.84 + age.85.up" [link and styling mine].