Elasticity in Microeconomics

Elasticity is a fundamental concept in microeconomics that measures how responsive quantity demanded or supplied is to changes in one of its determinants, such as price, income, or the price of related goods. Understanding elasticity helps explain consumer and producer behavior and informs policy decisions.

Elasticity of Demand

The elasticity of demand quantifies how much the quantity demanded of a good responds to changes in its determinants, most commonly price.

• Definition: Elasticity of demand is the measure of the responsiveness of quantity demanded (or supplied) to one of its determinants (price, income, etc.).

• Key Determinants:

  • Close Substitutes: The more substitutes available for a good, the more elastic its demand.

  • Necessities vs. Luxuries: Necessities tend to have inelastic demand, while luxuries are more elastic.

  • Scope/Definition of the Market: Narrowly defined markets (e.g., ice cream) have more elastic demand than broadly defined markets (e.g., food).

  • Time Horizon: Demand is more elastic over longer time horizons as consumers have more time to adjust their behavior.

Price Elasticity of Demand

Price elasticity of demand measures how much the quantity demanded of a good responds to a change in its price.

• Formula:

• Example: If the price of ice cream rises by 10% and quantity demanded falls by 20%, then:

• Absolute Value: Elasticity is often expressed as an absolute value, since the law of demand makes the value negative (exception: Giffen goods).

Classification of Elasticity

Elasticity values help classify demand curves and predict consumer responses.

• Elastic Demand: Elasticity greater than one (). Quantity demanded changes more than price.

• Inelastic Demand: Elasticity less than one (). Quantity demanded changes less than price.

• Unit Elasticity: Elasticity equals one (). Quantity demanded changes exactly as much as price.

Special Cases

• Perfectly Inelastic Demand: Elasticity equals zero; demand curve is vertical.

• Perfectly Elastic Demand: Elasticity is infinite; demand curve is horizontal.

Variety of Demand Curves

Demand curves can be classified based on their elasticity:

• Flatter demand curves indicate more elastic demand.

• Steeper demand curves indicate more inelastic demand.

Table: Classification of Demand Elasticity

True/False Questions (Demand)

• Demand for a good is inelastic if quantity demanded increases only slightly when price falls.

• Demand is inelastic if elasticity is less than one.

• If price elasticity of demand is equal to zero, demand is perfectly inelastic.

• The flatter the demand curve, the more elastic the demand.

• If demand is perfectly inelastic, the demand curve is vertical and elasticity is zero.

Elasticity of Supply

The elasticity of supply measures how much the quantity supplied of a good responds to changes in its price.

Price Elasticity of Supply

• Definition: Price elasticity of supply measures the response of quantity supplied to a change in price.

• Determinants:

  • Flexibility of Sellers: More fixed supply (e.g., beachfront property) is less elastic.

  • Time Horizon: Supply is more elastic in the long run than in the short run.

Computing Price Elasticity of Supply

• Formula:

• Example: If the price of milk increases by 10% and the quantity supplied rises by 20%, then:

Variety of Supply Curves

• Flatter supply curves indicate more elastic supply.

• Steeper supply curves indicate more inelastic supply.

Special Cases

• Perfectly Inelastic Supply: Elasticity equals zero; supply curve is vertical.

• Perfectly Elastic Supply: Elasticity is infinite; supply curve is horizontal.

Table: Classification of Supply Elasticity

True/False Questions (Supply)

• Price elasticity of supply measures how much the quantity supplied responds to changes in price.

• Supply is inelastic if quantity supplied responds only slightly to price changes.

• Supply tends to be more elastic in the long run.

• If supply curve is horizontal, supply is perfectly elastic and elasticity approaches infinity.

Applications of Elasticity

Elasticity concepts are widely used in economic analysis and policy-making.

• Revenue and Profit: Elasticity helps determine how changes in price affect total revenue and profit.

• Government Policies: Elasticity informs the impact of taxes, subsidies, and other interventions on markets.

Example Application: If demand is elastic, a price increase will decrease total revenue; if demand is inelastic, a price increase will increase total revenue.

Additional info: Elasticity is also used to analyze the effects of price controls, international trade policies, and welfare economics.