Every day, managers ask questions like “If we cut the price by 5 %, how many more units will we sell?” or “Does spending an extra dollar on advertising actually pay for itself?” To answer these questions with real numbers instead of hunches, we use a set of tools called regression analysis. In this chapter, you will learn how to estimate business relationships from data, how to read the numbers that statistical software gives you, and how to tell whether those numbers actually mean something.