elasticity

In economics, the degree to which demand or supply for a good responds to a change in price, income, or other factors; in physics, the ability of a material to return to its original shape after deformation.

• elastic/ɪˈlæstɪk/(adj)有弹性的
• inelastic/ˌɪnɪˈlæstɪk/(adj)缺乏弹性的

• price elasticity
• demand elasticity
• elastic demand
• inelastic supply
• elasticity of demand
• income elasticity

1. 1.Insulin has nearly zero price elasticity of demand — diabetics will pay almost any price because they have no substitute. Luxury handbags are highly elastic: raise the price and many buyers switch to alternatives. (price sensitivity)
2. 2.Gasoline demand is inelastic in the short term (people still need to commute) but more elastic long-term (people buy fuel-efficient cars or move closer to work). (time-dependent elasticity)

• responsiveness— how much something reacts to a change
• sensitivity— degree of reaction

from Greek "elastikos" (propulsive, driving) — from "elaunein" (to drive, to push) — how forcefully demand pushes back against price changes