Price elasticity of demand measures the responsiveness of demand after a change in price
The formula for calculating the co-efficient of elasticity of demand is:
Percentage change in quantity demanded divided by the percentage change in price
Since changes in price and quantity usually move in opposite directions, usually we do not bother to put in the minus sign. We are more concerned with the co-efficient of elasticity of demand
How much does quantity demanded change when price changes? By a lot or by a little? Elasticity can help us understand this question
Price elasticity of demand
Values for price elasticity of demand
If Ped = 0 demand is perfectly inelastic - demand does not change at all when the price changes – the demand curve will be vertical.
If Ped is between 0 and 1 (i.e. the % change in demand from A to B is smaller than the percentage change in price), then demand is inelastic.
If Ped = 1 (i.e. the % change in demand is exactly the same as the % change in price), then demand is unit elastic. A 15% rise in price would lead to a 15% contraction in demand leaving total spending the same at each price level.
If Ped > 1, then demand responds more than proportionately to a change in price i.e. demand is elastic. For example if a 10% increase in the price of a good leads to a 30% drop in demand. The price elasticity of demand for this price change is –3
Geoff Riley FRSA has been teaching Economics for nearly thirty years. He has twenty years experience as Head of Economics at leading schools. He writes extensively and is a contributor and presenter on CPD conferences in the UK and overseas.
This 44-page, full-colour printed revision guide is designed to support students preparing for their AS Economics exams on macroeconomics. tutor2u's Geoff Riley provides comprehensive coverage of all the core macroeconomic topics for AS Economics