Appendix A: Linear Algebra for Regression

Overview

This appendix provides the linear algebra foundations needed for understanding regression. We cover special matrix types (diagonal, idempotent, symmetric, positive definite, projection), and connect matrix theory to statistical results (quadratic forms, sampling distributions).

Learning Objectives

After completing this chapter, you should be able to understand and apply the key concepts covered in each section below.

Sections

Section	Topic
A.1	Square Matrices
A.2	Linear Algebra and Statistics