Linear Regression Revisited.

I always disliked when a book gives equations and formulas as if of fiat without providing justification or demonstration; and I don’t mind that they skip a few steps as long that I can fill in the blanks myself if I care to. Linear regression is one of those formula we see but we’d like to understand better.

So let us see how to derive the formulas for linear regression and see how they generalize to any number of unknowns.