2After studying this chapter you will be able to Define perfect competitionExplain how firms make their supply decisions and why they sometimes shut down temporarily and lay off workersExplain how price and output in an industry are determined and why firms enter and leave the industryPredict the effects of a change in demand and of a technological advanceExplain why perfect competition is efficient
3The Busy BeeThe busy bee pollinates plants and beekeepers rent their hives to farmers.Across the United States from Vermont to California, a parasite is killing off bees and the rent farmers pay for hives has more than doubled.How does competition in beekeeping and other industries affect prices and profits?We study a fiercely competitive market in this chapter.We explain the changes in price and output as the firms in perfect competition respond to changes in demand and technological advances.
4What Is Perfect Competition? Perfect competition is an industry in whichMany firms sell identical products to many buyers.There are no restrictions to entry into the industry.Established firms have no advantages over new ones.Sellers and buyers are well informed about prices.
5What Is Perfect Competition? How Perfect Competition ArisesPerfect competition arises:When firm’s minimum efficient scale is small relative to market demand so there is room for many firms in the industry.And when each firm is perceived to produce a good or service that has no unique characteristics, so consumers don’t care which firm they buy from.
6What Is Perfect Competition? Price TakersIn perfect competition, each firm is a price taker.A price taker is a firm that cannot influence the price of a good or service.No single firm can influence the price—it must “take” the equilibrium market price.Each firm’s output is a perfect substitute for the output of the other firms, so the demand for each firm’s output is perfectly elastic.
7What Is Perfect Competition? Economic Profit and RevenueThe goal of each firm is to maximize economic profit, which equals total revenue minus total cost.Total cost is the opportunity cost of production, which includes normal profit.A firm’s total revenue equals price, P, multiplied by quantity sold, Q, or P Q.A firm’s marginal revenue is the change in total revenue that results from a one-unit increase in the quantity sold.
8What Is Perfect Competition? Figure 11.1 illustrates a firm’s revenue concepts.Part (a) shows that market demand and market supply determine the market price that the firm must take.
9What Is Perfect Competition? Figure 11.1(b) shows the firm’s total revenue curve (TR)—the relationship between total revenue and quantity sold.
10What Is Perfect Competition? Figure 11.1(c) shows the marginal revenue curve (MR).The firm can sell any quantity it chooses at the market price, so marginal revenue equals price and the demand curve for the firm’s product is horizontal at the market price.
11What Is Perfect Competition? The demand for the firm’s product is perfectly elastic because one of Cindy’s sweaters is a perfect substitute for the sweater of another firm.The market demand is not perfectly elastic because a sweater is a substitute for some other good.
12The Firm’s Decisions in Perfect Competition A perfectly competitive firm faces two constraints:1. A market constraint summarized by the market price and the firm’s revenue curves.2. A technology constraint summarized by firm’s product curves and cost curves (like those in Chapter 10).The goal of the firm is to make maximum economic profit, given the constraints it faces.So the firm must make four decisions: Two in the short run and two in the long run.
13The Firm’s Decisions in Perfect Competition Short-Run DecisionsIn the short run, the firm must decide:1. Whether to produce or to shut down temporarily.2. If the decision is to produce, what quantity to produce.Long-Run DecisionsIn the long run, the firm must decide:1. Whether to increase or decrease its plant size.2. Whether to stay in the industry or leave it.
14The Firm’s Decisions in Perfect Competition Profit-Maximizing OutputA perfectly competitive firm chooses the output that maximizes its economic profit.One way to find the profit-maximizing output is to look at the firm’s the total revenue and total cost curves.Figure 11.2 on the next slide looks at these curves along with the firm’s total profit curve.
15The Firm’s Decisions in Perfect Competition Part (a) shows the total revenue, TR, curve.Part (a) also shows the total cost curve, TC, which is like the one in Chapter 10.Total revenue minus total cost is economic profit (or loss), shown by the curve EP in part (b).
16The Firm’s Decisions in Perfect Competition At low output levels, the firm incurs an economic loss—it can’t cover its fixed costs.At intermediate output levels, the firm makes an economic profit.
17The Firm’s Decisions in Perfect Competition At high output levels, the firm again incurs an economic loss—now the firm faces steeply rising costs because of diminishing returns.The firm maximizes its economic profit when it produces 9 sweaters a day.
18The Firm’s Decisions in Perfect Competition Marginal AnalysisThe firm can use marginal analysis to determine the profit-maximizing output.Because marginal revenue is constant and marginal cost eventually increases as output increases, profit is maximized by producing the output at which marginal revenue, MR, equals marginal cost, MC.Figure 11.3 on the next slide shows the marginal analysis that determines the profit-maximizing output.
19The Firm’s Decisions in Perfect Competition If MR > MC, economic profit increases if output increases.If MR < MC, economic profit decreases if output increases.If MR = MC, economic profit decreases if output changes in either direction, so economic profit is maximized.
20The Firm’s Decisions in Perfect Competition Profits and Losses in the Short RunMaximum profit is not always a positive economic profit.To determine whether a firm is making an economic profit or incurring an economic loss, we compare the firm’s average total cost at the profit-maximizing output with the market price.Figure 11.4 on the next slide shows the three possible profit outcomes.
21The Firm’s Decisions in Perfect Competition In part (a) price equals average total cost and the firm makes zero economic profit (breaks even).
22The Firm’s Decisions in Perfect Competition In part (b), price exceeds average total cost and the firm makes a positive economic profit.
23The Firm’s Decisions in Perfect Competition In part (c) price is less than average total cost and the firm incurs an economic loss—economic profit is negative.
24The Firm’s Decisions in Perfect Competition The Firm’s Short-Run Supply CurveA perfectly competitive firm’s short run supply curve shows how the firm’s profit-maximizing output varies as the market price varies, other things remaining the same.Because the firm produces the output at which marginal cost equals marginal revenue, and because marginal revenue equals price, the firm’s supply curve is linked to its marginal cost curve.But there is a price below which the firm produces nothing and shuts down temporarily.
25The Firm’s Decisions in Perfect Competition Temporary Plant ShutdownIf price is less than the minimum average variable cost, the firm shuts down temporarily and incurs an economic loss equal to total fixed cost.This economic loss is the largest that the firm must bear.If the firm were to produce just 1 unit of output at a price below minimum average variable cost, it would incur an additional (and avoidable) loss.
26The Firm’s Decisions in Perfect Competition The shutdown point is the output and price at which the firm just covers its total variable cost.This point is where average variable cost is at its minimum.It is also the point at which the marginal cost curve crosses the average variable cost curve.At the shutdown point, the firm is indifferent between producing and shutting down temporarily.It incurs a loss equal to total fixed cost from either action.
27The Firm’s Decisions in Perfect Competition If the price exceeds minimum average variable cost, the firm produces the quantity at which marginal cost equals price.Price exceeds average variable cost, and the firm covers all its variable cost and at least part of its fixed cost.
28The Firm’s Decisions in Perfect Competition Short-Run Supply CurveFigure 11.5 shows how the firm’s short-run supply curve is constructed.If price equals minimum average variable cost, $17 in this example, the firm is indifferent between producing nothing and producing at the shutdown point, T.
29The Firm’s Decisions in Perfect Competition If the price is $25, the firm produces 9 sweaters a day, the quantity at which P = MC.If the price is $31, the firm produces 10 sweaters a day, the quantity at which P = MC.The blue curve in part (b) traces the firm’s short-run supply curve.
30The Firm’s Decisions in Perfect Competition Short-Run Industry Supply CurveThe short-run industry supply curve shows the quantity supplied by the industry at each price when the plant size of each firm and the number of firms remain constant.
31The Firm’s Decisions in Perfect Competition Figure 11.6 shows the supply curve for an industry that has 1,000 firms like Cindy’s.The quantity supplied by the industry at any given price is the sum of the quantities supplied by all the firms in the industry at that price.
32The Firm’s Decisions in Perfect Competition At a price equal to minimum average variable cost—the shutdown price—the industry supply curve is perfectly elastic because some firms will produce the shutdown quantity and others will produces zero.
33Output, Price, and Profit in Perfect Competition Short-Run EquilibriumShort-run industry supply and industry demand determine the market price and output.Figure 11.7 shows a short-run equilibrium.
34Output, Price, and Profit in Perfect Competition A Change in DemandAn increase in demand bring a rightward shift of the industry demand curve: the price rises and the quantity increases.A decrease in demand bring a leftward shift of the industry demand curve: the price falls and the quantity decreases.
35Output, Price, and Profit in Perfect Competition Long-Run AdjustmentsIn short-run equilibrium, a firm may make an economic profit, break even, or incur an economic loss.Which of these outcomes occurs determines how the industry adjusts in the long run.In the long run, the firm may:Enter or exit an industryChange its plant size
36Output, Price, and Profit in Perfect Competition Entry and ExitNew firms enter an industry in which existing firms make an economic profit.Firms exit an industry in which they incur an economic loss.Figure 11.8 on the next slide shows the effects of entry and exit.
37Output, Price, and Profit in Perfect Competition Effects of EntryAs new firms enter an industry, industry supply increases.The industry supply curve shifts rightward.The price falls, the quantity increases, and the economic profit of each firm decreases.
38Output, Price, and Profit in Perfect Competition The Effects of ExitAs firms exit an industry, industry supply decreases.The industry supply curve shifts leftward.The price rises, the quantity decreases, and the economic loss of each firm remaining in the industry decreases.
39Output, Price, and Profit in Perfect Competition Changes in Plant SizeA firm changes its plant size whenever doing so is profitable.If average total cost exceeds the minimum long-run average cost, the firm changes its plant size to lower average costs and increase economic profit.Figure 11.9 on the next slide shows the effects of changes in plant size.
40Output, Price, and Profit in Perfect Competition If the price is $25 a sweater, the firm is making zero economic profit with the current plant.
41Output, Price, and Profit in Perfect Competition But if the LRAC curve is sloping downward at the current output, the firm can increase profit by expanding the plant.
42Output, Price, and Profit in Perfect Competition As the plant size increases, the firm’s short-run supply increases, the average total cost falls, and its economic profit increases.
43Output, Price, and Profit in Perfect Competition As all firms in the industry change their plant size, industry supply increases, the market price falls, and economic profit decreases.
44Output, Price, and Profit in Perfect Competition Long-run equilibrium occurs when each firm is producing at minimum long-run average cost and is making zero economic profit.
45Output, Price, and Profit in Perfect Competition Long-Run EquilibriumLong-run equilibrium occurs in a competitive industry when:Economic profit is zero, so firms neither enter nor exit the industry.Long-run average cost is at its minimum, so firms don’t change their plant size.
46Changing Tastes and Advancing Technology A Permanent Change in DemandA decrease in demand shifts the market demand curve leftward. The price falls and the quantity decreases.Figure illustrates the effects of a permanent decrease in demand when the industry is in long-run equilibrium.
47Changing Tastes and Advancing Technology A decrease in demand shifts the industry demand curve leftward. The market price falls, and each firm decreases the quantity it produces.
48Changing Tastes and Advancing Technology The market price is now below each firm’s minimum average total cost, so firms incur economic losses.
49Changing Tastes and Advancing Technology Economic losses induce some firms to exit, which decreases the industry supply and the price starts to rise.
50Changing Tastes and Advancing Technology As the price rises, the quantity produced by the industry continues to decrease as more firms exit, but each firm remaining in the industry starts to increase its quantity.
51Changing Tastes and Advancing Technology A new long-run equilibrium occurs when the price has risen to equal minimum average total cost. Firms do not incur economic losses, and firms no longer exit the industry.
52Changing Tastes and Advancing Technology The main difference between the initial and new long-run equilibrium is the number of firms in the industry.Fewer firms produce the equilibrium quantity.
53Changing Tastes and Advancing Technology A permanent increase in demand has the opposite effects to those just described and shown in Figure 11.9.An increase in demand shifts the demand curve rightward. The price rises and the quantity increases.Economic profit induces entry, which increases short-run supply and shifts the short-run industry supply curve rightward.As industry supply increases, the price falls and the market quantity continues to increase.
54Changing Tastes and Advancing Technology With a falling price, each firm decreases production in a movement along the firm’s marginal cost curve (short-run supply curve).A new long-run equilibrium occurs when the price has fallen to equal minimum average total cost so that firms do not make economic profits, and firms no longer enter the industry.The main difference between the initial and new long-run equilibrium is the number of firms in the industry. In the new equilibrium, a larger number of firms produce the equilibrium quantity.
55Changing Tastes and Advancing Technology External Economics and DiseconomiesThe change in the long-run equilibrium price following a permanent change in demand depends on external economies and external diseconomies.External economies are factors beyond the control of an individual firm that lower the firm’s costs as the industry output increases.External diseconomies are factors beyond the control of a firm that raise the firm’s costs as industry output increases.
56Changing Tastes and Advancing Technology In the absence of external economies or external diseconomies, a firm’s costs remain constant as industry output changes.Figure illustrates the three possible cases and shows the long-run industry supply curve.The long-run industry supply curve shows how the quantity supplied by an industry varies as the market price varies after all the possible adjustments have been made, including changes in plant size and the number of firms in the industry.
57Changing Tastes and Advancing Technology Figure 11.11(a) shows that in the absence of external economies or external diseconomies, an increase in demand does not change the price in the long run.The long-run industry supply curve LSA is horizontal.
59Changing Tastes and Advancing Technology Figure 11.11(b) shows that when external diseconomies are present, an increase in demand brings a higher price in the long run.The long-run industry supply curve LSB is upward sloping.
61Changing Tastes and Advancing Technology Figure 11.11(c) shows that when external economies are present, an increase in demand brings a lower price in the long run.The long-run industry supply curve LSC is downward sloping.
63Changing Tastes and Advancing Technology Technological ChangeNew technologies are constantly discovered that lower costs.A new technology enables firms to produce at a lower average cost and a lower marginal cost—firms’ cost curves shift downward.Firms that adopt the new technology make an economic profit.
64Changing Tastes and Advancing Technology New-technology firms enter and old-technology firms either exit or adopt the new technology.Industry supply increases and the industry supply curve shifts rightward.The price falls and the quantity increases.Eventually, a new long-run equilibrium emerges in which all firms use the new technology, the price equals minimum average total cost, and each firm makes zero economic profit.
65Competition and Efficiency Efficient Use of ResourcesResources are used efficiently when no one can be made better off without making someone else worse off.This situation arises when marginal social benefit equals marginal social cost.
66Competition and Efficiency Choices, Equilibrium, and EfficiencyWe can describe an efficient use of resources in terms of the choices of consumers and firms coordinated in market equilibrium.ChoicesA consumer’s demand curve shows how the best budget allocation changes as the price of a good changes.So consumers get the most value out of their resources at all points along their demand curves.With no external benefits, the market demand curve is the marginal social benefit curve.
67Competition and Efficiency A competitive firm’s supply curve shows how the profit-maximizing quantity changes as the price of a good changes.So firms get the most value out of their resources at all points along their supply curves.With no external cost, the market supply curve is the marginal social cost curve.
68Competition and Efficiency Equilibrium and EfficiencyIn competitive equilibrium, resources are used efficiently—the quantity demanded equals the quantity supplied, so marginal social benefit equals marginal social cost.The gains from trade for consumers is measured by consumer surplus.The gains from trade for producers is measured by producer surplus.Total gains from trade equal total surplus, and in long-run equilibrium total surplus is maximized.
69Competition and Efficiency Figure illustrates an efficient allocation of resources in a perfectly competitive industry.In part (a), each firm is producing at the lowest possible long-run average total cost at the price P* and the quantity q*.
73Competition and Efficiency The quantity Q* and price P* are the competitive equilibrium values.So competitive equilibrium is efficient.Total surplus, the sum of consumer surplus andproducer surplus is maximized.