# Tag Info

The answer is largely the same whether we consider $\ell_1$ or $\ell_2$ regularisation, so I will just speak generally about regularisation. Mean square error for training data Given some training data $\{(x_i, y_i)\}_{i = 1}^n$, a linear regression line $Y = aX + b$ fit using the least squares method looks for coefficients that minimise the sum of squares, ...