Compute the midpoint price elasticity of demand and classify the good as elastic, inelastic, or unit-elastic.
用中点法计算需求对价格的弹性,避免端点依赖。
| Item | Formula / Note | Source / Standard |
|---|---|---|
| Price elasticity of demand | Ed = (ΔQ/Q) / (ΔP/P); arc elasticity uses the midpoint method | Alfred Marshall (1890), Principles of Economics |