arc elasticity  the price elasticity of demand measured over a price range using the midpoint, or average, as the base
cross-price elasticity of demand  the percentage change in the demand for one good divided by the percentage change in the price of a related good, ceteris paribus
income elasticity of demand  the percentage change in the demand for a good divided by the percentage change in income, ceteris paribus
inferior goods  goods for which the income elasticity of demand is negative
long run  a period of time long enough that the quantities of all resources can be varied
normal goods  goods for which the income elasticity of demand is positive
perfectly elastic demand curve  a horizontal demand curve indicating that consumers can and will purchase all they want at one price
perfectly inelastic demand curve  a vertical demand curve indicating that there is no change in the quantity demanded as the price changes
price discrimination  charging different customers different prices for the same product
price elasticity of demand  the percentage change in the quantity demanded of a product divided by the percentage change in the price of that product
price elasticity of supply  the percentage change in quantity supplied divided by the percentage change in price, ceteris paribus
short run  a period of time short enough that the quantities of at least some of the resources cannot be varied
tax incidence  a measure of who pays a tax
total revenue(TR)  TR 5 P 3 Q