Elasticity

Measure of how strongly quantity demanded or supplied responds to a change in price, income, or another driver.

Specifications & Metrics

Marshall defined price elasticity of demand as the percentage quantity response to a one percent price change.
Demand for necessities like salt is inelastic; demand for luxuries tends to be elastic.
Firms facing inelastic demand can raise price without losing much volume, which is why elasticity measures pricing power.