The Machine Learning “Advent Calendar” Day 11: Linear Regression in Excel

Linear Regression looks simple, but it introduces the core ideas of modern machine learning: loss functions, optimization, gradients, scaling, and interpretation. In this article, we rebuild Linear Regression in Excel, compare the closed-form solution with Gradient Descent, and see how the coefficients evolve step by step. This foundation naturally leads to regularization, kernels, classification, and the dual view. Linear Regression is not just a straight line, but the starting point for many models we will explore next in the Advent Calendar.