Chapter 9: Concise

Monopoly Characteristics

  • Single Seller: Only one firm in the market.
  • Unique Product: No close substitutes available.
  • Barriers to Entry:
    • Ownership of Vital Resource: Exclusive access (e.g., water resources, sports leagues).
    • Legal Barriers: Regulatory restrictions.
    • Economies of Scale: Larger firms often operate more efficiently, leading to a natural monopoly.
    • Network Goods: Value increases with more users (e.g., social media).

Price Maker

  • Definition: Monopoly has the power to set prices due to a downward-sloping demand curve.
  • Price Choice: Determine price ($Pm$) from quantity ($Qm$) using demand curve.
    • Demand Equation: $P = a - bQ$, where $a, b > 0$.
    • Profit Calculation: ext{Profit} = TR - TC; ext{TR} = P imes Q.
    • Marginal Revenue: MR = a - 2bQ.
    • Marginal Cost: MC = rac{ ext{d}TC}{ ext{d}Q}.
    • Optimal output at MR = MC.

Monopoly Limitations

  • Slope of Demand Curve: Determines monopoly power, defined by Lerner Index:
    M.P. = rac{P - MC}{P} = 1 - rac{MC}{P} = rac{1}{|E_d|}.
  • Relationship: Higher elasticity implies lower monopoly power and vice versa.

Cost Function in Short Run vs Long Run

  • Profit Scenarios:
    i. Profit ($ ext{π} > 0$): $Pm > ATC$ ii. Break-Even ($ ext{π} = 0$): $Pm = ATC$
    iii. Loss ($ ext{π} < 0$): $P_m < ATC$

Welfare Analysis

  • Consumer Surplus (CS): Area above price and below demand curve.
  • Producer Surplus (PS): Area below price and above supply curve.
  • Total Surplus (TS): TS = CS + PS.
  • Deadweight Loss (DWL): Efficiency loss; minimized under perfect competition where P = SRMC.

Price Discrimination

  • Definition: Charging different prices for the same product based on consumer type.
  • Conditions:
    1. Downward-sloping demand curve.
    2. Ability to distinguish consumers.
    3. No arbitrage between consumers.
  • Examples: Movie tickets, hardcover vs paperback books, coupons.
  • Behavioral Insight: Higher prices charged to consumers with less elastic demand.
  • Perfect Price Discrimination: No deadweight loss by charging each consumer based on their individual willingness to pay.