This document provides an introduction to regression analysis. It discusses correlation as a technique to measure relationships between two variables. Regression allows using the value of one variable to predict the value of another when a consistent relationship exists. The goal of regression is to find the equation of the best fitting straight line for a set of data. This line can be expressed as an equation relating the total cost (Y) variable to the number of hours (X) variable. The best fitting line minimizes the sum of the squared distances between the data points and the line. This process results in a regression equation that can be used to predict Y values given X values. However, predictions should only be made within the range of the original data.