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ECON 201 PRINCIPLES OF MICROECONOMICS. Chapter 5. Professor Carol Cui. Recall: Allocative efficiency of a good occurs at the point where its Marginal Cost equals its Marginal Benefit. MC, MB ($). MC. P *. MB. Q. Q *. If MB > MC (underproduction), production needs to increase.
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ECON 201 PRINCIPLES OF MICROECONOMICS Chapter 5 Professor Carol Cui
Recall: Allocative efficiency of a good occurs at the point where its Marginal Cost equals its Marginal Benefit. MC, MB ($) MC P* MB Q Q* If MB > MC (underproduction), production needs to increase. If MC > MB (overproduction), production needs to decrease.
MB vs. Demand Curve • More on MB: • The value of one more unit of a good is its marginal benefit. • MB is measured by the maximum price that is willingly paid for another unit of the good. • Thus, willingness to pay determines demand. A demand curve is a marginal benefit curve.
Consumer Surplus • When people buy something for less than it is worth to them, they receive a consumer surplus. • Consumer surplus is the value of a good a consumer would pay minus the price the consumer actually paid, summed over the quantity bought.
Consumer Surplus CS: The area under a demand curve and above the price line. $7 CS $3 TR D = MB 0 40 TR: Total Revenue is the blue rectangular
MC vs. Supply Curve • Recall: • The cost of producing one more unit of a good is its marginal cost. • MC is the minimum price that producers must receive to induce them to offer one more unit of a good for sale. • Thus, minimum-supply price determines demand. A supply curve is a marginal cost curve.
Producer Surplus • When price exceeds marginal cost, the firm receives a producer surplus. • Producer surplus is the price a producer actually receives for a good minus the minimum price the producer would have been willing to supply the good, summed over the quantity bought.
Producer Surplus P S = MC PS: The area under the price line and above the supply curve. PS Cost of Production Q
Efficiency of Competitive Equilibrium At the equilibrium where supply and demand curves cross, we get the largest total surplus (i.e. consumer surplus + producer surplus). Thus, the competitive equilibrium is the most efficient allocation of resources. P S = MC PE D = MB Q QE
Deadweight Loss • The decrease in total surplus that results from an inefficient level of production (i.e. produce less than or more than the equilibrium quantity) • Measure the scale of inefficiency • Could be a loss of consumer or producer surplus, but it is a loss which is no one’s gain.
Underproduction P Deadweight Loss S PE D Q Q QE
Overproduction P($) S Deadweight Loss PE D Q Q QE At production level Q, the area of deadweight loss must be subtracted from the area of CS plus PS to obtain the true surplus area.
What Causes Deadweight Loss? • Price Regulations (Ch 6) • Price Ceiling • Price Floor • Taxes, Subsidies, Quotas (Ch 6) • Monopoly (Ch 12) • Externalities • e.g. pollution (external cost), flu vaccine (external benefit)