38. Video: Working With Categorical Variables Refresher

Notice that in the earlier video in the pre-requisites, there was a mention of dropping a column to assure your X matrix is full rank. This is not true using LinearRegression within sklearn, because there is a ridge (or L2 penalty used by default). However, dropping the columns would also be okay, it is just not required, as it is with OLS without a penalty.

You will see this holds true in the upcoming content.