Price Controls and Elasticity in Microeconomics: Study Notes

Price Controls in Microeconomics

Price Ceilings and Price Floors

Price controls are government-imposed limits on the prices that can be charged for goods and services in a market. The two main types are price ceilings and price floors.

• Price Ceiling: A legally established maximum price that sellers may charge for a good or service. It is effective only if set below the equilibrium price.

• Price Floor: A legally established minimum price that buyers must pay for a good or service. It is effective only if set above the equilibrium price.

Example: Rent control is a classic example of a price ceiling, where the government sets a maximum price landlords can charge for rent.

Effects of Price Ceilings

• Creates a shortage in the market because the quantity demanded exceeds the quantity supplied at the controlled price.

• Results in increased quantity demanded and decreased quantity supplied.

• May lead to the formation of illegal markets (black markets) where the good is sold at higher prices.

• Some consumer surplus may be converted to producer surplus or lost entirely.

Example: Imposing a rent ceiling below the equilibrium rent increases the number of people seeking apartments but reduces the number of apartments offered for rent.

Minimum Wage as a Price Floor

• The minimum wage is an example of a price floor, setting the lowest legal wage that can be paid to workers.

• If set above the equilibrium wage, it can create a surplus of labor (unemployment).

Equilibrium Price

• The equilibrium price is the price at which the quantity supplied equals the quantity demanded.

• Price controls disrupt the natural movement toward equilibrium.

Elasticity in Microeconomics

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:

$\text{Price Elasticity of Demand} = \frac{\%\ \text{change in quantity demanded}}{\%\ \text{change in price}}$

• If the value is greater than 1 (in absolute value), demand is elastic.

• If the value is less than 1 (in absolute value), demand is inelastic.

• If the value equals 1, demand is unit elastic.

• If the value is 0, demand is perfectly inelastic (quantity demanded does not change with price).

• If the value is infinity, demand is perfectly elastic (quantity demanded drops to zero with any price increase).

Example: If a 10% increase in price leads to a 20% decrease in quantity demanded, the price elasticity of demand is -2 (elastic demand).

Interpreting Elasticity Values

• Elastic Demand: Consumers are highly responsive to price changes (e.g., luxury goods).

• Inelastic Demand: Consumers are not very responsive to price changes (e.g., necessities like insulin).

• Unit Elastic: Percentage change in quantity demanded equals the percentage change in price.

Determinants of Price Elasticity of Demand

• Availability of Substitutes: More substitutes make demand more elastic.

• Share of Budget: Goods that take up a larger portion of a consumer's budget tend to have more elastic demand.

• Necessity vs. Luxury: Necessities tend to have inelastic demand; luxuries are more elastic.

• Time Horizon: Demand is usually more elastic in the long run.

Example: The demand for salt is inelastic because it is a necessity and represents a small share of most consumers' budgets.

Calculating Elasticity: Examples

• If the price of a good increases by 15% and the price elasticity of demand is -0.3, the quantity demanded will decrease by 4.5%.

• If the price of tortilla chips rises by 10% and quantity demanded falls by 4%, the demand is inelastic (elasticity = -0.4).

Special Cases of Elasticity

• Perfectly Inelastic Demand: Quantity demanded does not change as price changes (vertical demand curve).

• Perfectly Elastic Demand: Any price increase causes quantity demanded to fall to zero (horizontal demand curve).

Example: The demand for insulin for diabetics is nearly perfectly inelastic.

Applications and Implications

• Understanding elasticity helps predict the effects of price changes, taxes, and subsidies on markets.

• Goods with inelastic demand generate more revenue when prices rise, while goods with elastic demand generate less.

Summary Table: Types of Price Elasticity of Demand

Type	Elasticity Value	Description	Demand Curve Shape
Perfectly Inelastic	0	Quantity demanded does not change with price	Vertical
Inelastic	0 < |E| < 1	Quantity demanded changes less than price	Steep
Unit Elastic	|E| = 1	Quantity demanded changes by the same percentage as price	Intermediate slope
Elastic	|E| > 1	Quantity demanded changes more than price	Flat
Perfectly Elastic	Infinity	Any price increase drops quantity demanded to zero	Horizontal

Key Terms

• Price Ceiling: Maximum legal price for a good or service.

• Price Floor: Minimum legal price for a good or service.

• Equilibrium Price: Price at which quantity supplied equals quantity demanded.

• Elasticity: Measure of responsiveness of one variable to changes in another.

• Price Elasticity of Demand: Responsiveness of quantity demanded to a change in price.

• Inelastic Demand: Demand that is not very responsive to price changes.

• Elastic Demand: Demand that is very responsive to price changes.