Table 48.1 An Elasticity Menagerie

NameElasticity valuesSignificance
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Perfectly inelastic demand0Price has no effect on quantity demanded (vertical demand curve).
Inelastic demandBetween 0 and 1A rise in price increases total revenue.
Unit-elastic demandExactly 1Changes in price have no effect on total revenue.
Elastic demandGreater than 1, less than ∞A rise in price reduces total revenue.
Perfectly elastic demandA rise in price causes quantity demanded to fall to 0. A fall in price leads to an infinite quantity demanded (horizontal demand curve).
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ComplementsNegativeQuantity demanded of one good falls when the price of another rises.
SubstitutesPositiveQuantity demanded of one good rises when the price of another rises.
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Inferior goodNegativeQuantity demanded falls when income rises.
Normal good, income-inelasticPositive,less than 1Quantity demanded rises when income rises,but not as rapidly as income.
Normal good, income-elasticGreater than 1Quantity demanded rises when income rises, and more rapidly than income.
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Perfectly inelastic supply0Price has no effect on quantity supplied (vertical supply curve).
Inelastic supplyBetween 0 and 1Upward-sloping supply curve
Unit-elastic supplyExactly 1Upward-sloping supply curve
Elastic supplyGreater than 1, less than ∞Upward-sloping supply curve
Perfectly elastic supplyAny fall in price causes quantity supplied to fall to 0. Any rise in price elicits an infinite quantity supplied (horizontal supply curve).