Elasticity and Responsiveness
Elasticity &
Responsiveness.
Direction is only the beginning. Elasticity measures how strongly buyers, sellers and economies respond when prices, incomes or other conditions change.
Observe
Measure the strength of response.
Two markets may move in the same direction—
but by very different amounts.
When price rises, demand usually falls. Yet a commuter may barely reduce essential fuel use, while a holiday traveller may quickly abandon an expensive destination. Elasticity measures this difference in responsiveness.
ASK THE SECOND QUESTION
After asking “Which direction?”, ask “By what percentage—and compared with what percentage change in the cause?”
Think
Use percentage changes.
Elasticity creates a
unit-free comparison.
Because percentage changes are independent of measurement units, elasticity allows comparison across different goods and markets. Demand elasticity is normally negative, reflecting the inverse price–quantity relationship, but classification usually uses its absolute value.
Ed = %ΔQd / %ΔPMidpoint method: %ΔQ = (Q₂−Q₁)/[(Q₁+Q₂)/2] × 100, and similarly for price.
Elastic: quantity responds proportionately more.
Unit elastic: proportional responses are equal.
Inelastic: quantity responds proportionately less.
Analyse
Calculate the response.
Build your own
elasticity experiment.
Start from price €10 and quantity 100. Choose a new price and quantity; the laboratory applies the midpoint formula and evaluates total revenue.
Demand elasticity laboratory
MIDPOINT METHOD
Price change
Initial price: €10
Quantity response
Initial quantity: 100
% PRICE CHANGE18.18%% QUANTITY CHANGE−22.22%|ELASTICITY|1.22CLASSIFICATIONElasticRevenue falls from €1,000 to €960.
With elastic demand, price and total revenue move in opposite directions.
Apply
Interpret constraints and policy.
Responsiveness depends on
available alternatives.
Demand becomes more elastic when close substitutes exist, the good absorbs a large budget share, consumers have time to adjust, or the market is narrowly defined. The less elastic side of a market generally bears more of a tax burden.
More alternatives
Buyers can switch more easily, making demand more elastic.
Longer adjustment
Households and firms can change technology and habits.
Essential consumption
Fewer avoidable purchases often make demand inelastic.
Lower responsiveness
The less elastic side has fewer escape options and bears more burden.
Decide
Connect elasticity and revenue.
Will a price increase
raise total revenue?
A railway estimates the absolute price elasticity of demand for peak-time tickets at 0.4.
MODULE 07 · CHECKPOINT
You can now measure
economic responsiveness.
Elasticity turns qualitative direction into quantitative sensitivity. It helps explain revenue, adjustment, tax incidence and the effectiveness of policy.
