Imagine you run a coffee shop chain and you’re thinking about cutting the price of a latte by 30 cents. How many more lattes will you sell? Will the extra sales make up for the lower price? And if a rival launches a big ad campaign, how much of your business will you lose? This chapter gives you tools to answer these “what if” questions with numbers, not guesses. You’ll learn how to turn raw data into a demand equation, pull out the responsiveness—or elasticity—of sales to price, income, and advertising, and then use that equation to forecast future sales.