Price elasticity of demand measures the percentage change in quantity demanded resulting from a 1 percent change in price. The value of the elasticity of demand for a product varies depending on the level of price and quantity at which it is evaluated. In other words, at different combinations of price and quantity demanded, the elasticity of demand for a particular product can vary significantly. As a convention, elasticity measures reported in the literaturecountries, and individuals are typically evaluated at the mean value of price and quantity in the data used in the estimation. In practice, the price elasticity of demand will always be negative. This indicates that as the price of a good increases all other factors held constant, consumers will demand less of that good. The magnitude of the elasticity estimate provides a measure of how responsive demand is. If the value of the price elasticity estimate is greater than one in absolute value, then demand is said to be elastic. When demand is elastic, consumers are very responsive to changes in price. As such, a small price change will lead to a relatively large change in quantity demanded. In contrast, if the value of the elasticity of demand estimate is less than one in absolute value, then demand is said to be inelastic and consumers are not very responsive to price changes. The demand for health care services is expected to be relatively inelastic, in large part because there are few close substitutes for medical services.