The magnitude of consumer responses to changes in a product market’s (or industry’s) price is measured by the own-price elasticity of demand, which equals the percentage change in a product market’s sales that results from a 1 percent change in price. If an industry raises price and consequently loses most of its customers to another industry (or industries), we conclude that the market under consideration faces close substitute products (or the product market competes with other product markets). Measuring the own-price elasticity of demand tells us whether a product faces close substitutes, but it does not identify what those substitutes might be. We can identify substitutes by measuring the cross-price elasticity of demand between two products. The cross-price elasticity measures the percentage change in demand for good Y that results from a 1- percent change in good X. The higher is the cross-price elasticity, the more readily consumers substitute between two goods when the price of one good is increased.