sm.add_constants()

Hi Anuridh, Thanks for reaching out. OLS requires the input to have a column of ones. We need to add this column manually.

x = sm.add_constant(x1) 

adds a column of ones to the x1 array (data['SAT']). Here is the head of x: As you can see, a column of ones is added to SAT. This column of ones corresponds to x_0 in the simple linear regression equation: y_hat = b_0 * x_0 + b_1 * x_1. As explained in the lecture video, x_0 is always one and thus the regression equation becomes: y_hat = b_0 * 1 + b_1 * x_1. The x array holds 1 and x_1. Best,
The 365 Team

thanks for the answer data365 team, currently learn your course on udemy. and im dying to know what is add_contsant do lol