Notes on Elasticity of Demand

  • Elasticity of Demand: It measures how much the quantity demanded of a good responds to a change in price.

    • Formula:
      E_d = \frac{\text{Percentage Change in Quantity Demanded}}{\text{Percentage Change in Price}}
    • This gives a numerical value indicating elasticity:
    • If |$E_d| > 1$, demand is elastic
    • If |$E_d| < 1$, demand is inelastic
    • If |$E_d| = 1$, demand is unit elastic

  • Calculation Example:

    • If the price of a product increases by 20% and the price elasticity of demand for the product is 0.5,
    • Using the formula, you can determine the percentage change in quantity demanded:
      • 0.5 = Percentage Change in Quantity Demanded / 20%
      • Solve for Percentage Change in Quantity Demanded:
        \text{Percentage Change in Quantity Demanded} = \frac{20\%}{2} = 10\%

  • Characteristics of Elasticity:

    • Elastic Demand: More responsive to price changes; consumers buy much less if the price rises.
    • Example: Luxury items like high-end electronics.
    • Inelastic Demand: Less responsive to price changes; consumers will buy almost the same quantity regardless of price spikes.
    • Example: Necessities like insulin.

  • Determinants of Price Elasticity:

    • Availability of Substitutes: More substitutes = more elastic demand.
    • If a product has many close substitutes, like different brands of coffee, demand will be more elastic.
    • Necessity vs. Luxury: Necessities tend to have inelastic demand due to lack of substitutes.
      • Example: Toilet paper is a necessity, hence inelastic.
    • Example: New gadgets are luxuries and tend to be more elastic.
    • Proportion of Income: Goods that take up a larger portion of income tend to have more elastic demand.
      • Example: Buying a car vs. buying bread.
    • Time Horizon: Longer time periods generally allow consumers to find substitutes, increasing elasticity.

  • Total Revenue Test:

    • Analyzes the relationship between price changes and revenue.
    • If price increases lead to increased total revenue, the demand is inelastic.
    • If price increases lead to decreased total revenue, the demand is elastic.

  • Graphical Representation:

    • The steeper the demand curve, the more inelastic the demand (and vice versa for elastic).
    • Perfectly Elastic Demand: Demand curve is horizontal (e.g., perfectly competitive market).
    • Perfectly Inelastic Demand: Demand curve is vertical (e.g., life-saving medication).

  • Real Life Applications of Elasticity:

    • This concept impacts pricing, marketing strategies, and understanding consumer behavior.
    • Businesses leverage elasticity understanding to predict how a price change will affect demand and overall sales.

  • Examples to Practice:

    • Given a price increase of a hot drink from $3 to $4 and a decreased demand from 50 to 40 units, find the elasticity.
      • Use the formula and remember:
        E_d = \frac{\frac{40 - 50}{50}}{\frac{4 - 3}{3}} to evaluate elasticity.
    • Analyzing the demand graph helps determine which part of the demand curve is more elastic or inelastic based on price levels.