Unit 5: Elasticity

Lesson 5.1: Price Elasticity of Demand

This section introduces the concept of elasticity in microeconomics, focusing on how consumers respond to changes in price and other factors. Understanding elasticity is crucial for analyzing market behavior and predicting the effects of price changes on demand.

What is Elasticity?

• Elasticity measures the responsiveness of one variable to changes in another variable, typically expressed as a percentage change.

• In economics, elasticity is most often used to analyze how quantity demanded or supplied responds to changes in price or other factors.

• General Formula:

• Because elasticity uses percentages, it is independent of the units of measurement for quantity and price.

Consumer Price Responsiveness

• When price changes, the quantity demanded will change; the magnitude of this change depends on how responsive consumers are.

• Graphical representation: A steeper demand curve indicates less responsiveness (inelastic), while a flatter curve indicates greater responsiveness (elastic).

• Example: If the price of a product drops and consumers buy much more, demand is considered elastic.

Price Elasticity of Demand

• Price Elasticity of Demand measures how responsive the quantity demanded is to a change in price.

• Formula:

• Elasticity is not the slope of the demand curve, but rather the percentage change along the curve.

Calculating the Elasticity

• Even if the slope of the demand curve is constant, the elasticity will change as we move along the curve.

• To calculate elasticity correctly between two points, use the average values (midpoint method).

Midpoint Formula

• Midpoint (Arc) Formula:

• This formula uses the average of the initial and final quantities and prices to determine elasticity between two points.

Interpreting Price Elasticity of Demand

• The quantity purchased always increases as the price falls, so the price elasticity of demand is always negative.

• By convention, economists often refer to the absolute value of elasticity (ignore the negative sign).

Classifications of Price Elasticity of Demand

• Inelastic Demand: Elasticity between 0 and -1 (absolute value between 0 and 1). The percentage change in quantity is less than the percentage change in price.

• Unit Elastic Demand: Elasticity equal to -1 (absolute value 1). The percentage change in quantity equals the percentage change in price.

• Elastic Demand: Elasticity below -1 (absolute value above 1). The percentage change in quantity is greater than the percentage change in price.

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

Additional info: Elasticity is a foundational concept in microeconomics, used to analyze consumer and producer behavior, set pricing strategies, and predict market outcomes. The midpoint formula is preferred for accuracy when calculating elasticity between two points on a demand curve.