1. 1 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics

2. 2 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics

3. 3 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics The Kindle can download books wirelessly. The Kindle experienced steady sales in the months following its introduction, and then it received a huge boost from talk-show host Oprah Winfrey. Consumer Choice and Behavioral Economics CHAPTER 9 Fernando Quijano Prepared by:

4. 4 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics 9.1Utility and Consumer Decision Making Define utility and explain how consumers choose goods and services to maximize their utility. 9.2Where Demand Curves Come From Use the concept of utility to explain the law of demand. 9.3Social Influences on Decision Making Explain how social influences can affect consumption choices. 9..4Behavioral Economics: Do People Make Their Choices Rationally? Describe the behavioral economics approach to understanding decision making. Appendix: Using Indifference Curves and Budget Lines to Understand Consumer Behavior Use indifference curves and budget lines to understand consumer behavior. CHAPTER 9 Chapter Outline and Learning Objectives Consumer Choice and Behavioral Economics

5. 5 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Utility and Consumer Decision Making The Economic Model of Consumer Behavior in a Nutshell The economic model of consumer behavior predicts that consumers will choose to buy the combination of goods and services that makes them as well off as possible from among all the combinations that their budgets allow them to buy. Utility Utility The enjoyment or satisfaction people receive from consuming goods and services. Define utility and explain how consumers choose goods and services to maximize their utility. 9.1 LEARNING OBJECTIVE

6. 6 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Utility and Consumer Decision Making Marginal utility (MU) The change in total utility a person receives from consuming one additional unit of a good or service. Law of diminishing marginal utility The principle that consumers experience diminishing additional satisfaction as they consume more of a good or service during a given period of time. The Principle of Diminishing Marginal Utility Define utility and explain how consumers choose goods and services to maximize their utility. 9.1 LEARNING OBJECTIVE

7. 7 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Utility and Consumer Decision Making FIGURE 9-1 Total and Marginal Utility from Eating Pizza on Super Bowl Sunday The Principle of Diminishing Marginal Utility The figure shows that for the first 5 slices of pizza, the more you eat, the more your total satisfaction, or utility, increases. If you eat a sixth slice, you start to feel ill from eating too much pizza, and your total utility falls. Each additional slice increases your utility by less than the previous slice, so your marginal utility from each slice is less than the one before. Panel (a) shows your total utility rising as you eat the first 5 slices and falling with the sixth slice. Panel (b) shows your marginal utility falling with each additional slice you eat and becoming negative with the sixth slice. The height of the marginal utility line at any quantity of pizza in panel (b) represents the change in utility as a result of consuming that additional slice. For example, the change in utility as a result of consuming 4 slices instead of 3 is 6 utils, so the height of the marginal utility line in panel (b) for the fourth slice is 6 utils. Define utility and explain how consumers choose goods and services to maximize their utility. 9.1 LEARNING OBJECTIVE

8. 8 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Utility and Consumer Decision Making The Rule of Equal Marginal Utility per Dollar Spent Budget constraint The limited amount of income available to consumers to spend on goods and services. Table 9-1 Total Utility and Marginal Utility from Eating Pizza and Drinking Coke NUMBER OF SLICES OF PIZZA TOTAL UTILITY FROM EATING PIZZA MARGINAL UTILITY FROM THE LAST SLICE NUMBER OF CUPS OF COKE TOTAL UTILITY FROM DRINKING COKE MARGINAL UTILITY FROM THE LAST CUP 0 0 -- 0 0 1 20 1 2 3616 2 3515 3 4610 3 4510 4 526 4 505 5 542 5 533 6 51 33 6 52 11 Define utility and explain how consumers choose goods and services to maximize their utility. 9.1 LEARNING OBJECTIVE

9. 9 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Utility and Consumer Decision Making The Rule of Equal Marginal Utility per Dollar Spent (1) SLICES OF PIZZA (2) MARGINAL UTILITY (MU PIZZA ) (3) MARGINAL UTILITY PER DOLLAR (4) CUPS OF COKE (5) MARGINAL UTILITY (MU COKE ) (6) MARGINAL UTILITY PER DOLLAR 12010120 2168215 31053 463455 521533 6 33  1.5 6 11 Table 9-2 Converting Marginal Utility to Marginal Utility per Dollar Define utility and explain how consumers choose goods and services to maximize their utility. 9.1 LEARNING OBJECTIVE

10. 10 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Utility and Consumer Decision Making COMBINATIONS OF PIZZA AND COKE WITH EQUAL MARGINAL UTILITIES PER DOLLAR MARGINAL UTILITY PER DOLLAR (MARGINAL UTILITY/PRICE)TOTAL SPENDINGTOTAL UTILITY 1 slice of pizza and 3 cups of Coke10$2 + $3 = $520 + 45 = 65 3 slices of pizza and 4 cups of Coke5$6 + $4 = $1046 + 50 = 96 4 slices of pizza and 5 cups of Coke3$8 + $5 = $1352 + 53 = 105 Table 9-3 Equalizing Marginal Utility per Dollar Spent The Rule of Equal Marginal Utility per Dollar Spent We can summarize the two conditions for maximizing utility: 1. 2. Spending on pizza + Spending on Coke = Amount available to be spent Define utility and explain how consumers choose goods and services to maximize their utility. 9.1 LEARNING OBJECTIVE

11. 11 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Solved Problem 9-1 Finding the Optimal Level of Consumption NUMBER OF ICE CREAM CONES TOTAL UTILITY FROM ICE CREAM CONES MARGINAL UTILITY FROM LAST CONE NUMBER OF CANS OF LIME FIZZ TOTAL UTILITY FROM CANS OF LIME FIZZ MARGINAL UTILITY FROM LAST CAN 00 --00 130 140 2552527535 37520310126 49015411918 510010513415 6105561417 Define utility and explain how consumers choose goods and services to maximize their utility. 9.1 LEARNING OBJECTIVE

12. 12 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Solved Problem 9-1 Finding the Optimal Level of Consumption (continued) ICE CREAM CONESCANS OF LIME FIZZ QUANTITYMU 1301540 22512.535 3201026 4157.518 510515 652.577 YOUR TURN: For more practice, do related problems 1.7 and 1.8 at the end of this chapter. Define utility and explain how consumers choose goods and services to maximize their utility. 9.1 LEARNING OBJECTIVE

13. 13 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Utility and Consumer Decision Making What if the Rule of Equal Marginal Utility per Dollar Does Not Hold? Don’t Let This Happen to YOU! Equalize Marginal Utilities per Dollar The idea of getting the maximum utility by equalizing the ratio of marginal utility to price for the goods you are buying can be difficult to grasp. Define utility and explain how consumers choose goods and services to maximize their utility. 9.1 LEARNING OBJECTIVE YOUR TURN: Test your understanding by doing elated problem 1.10 at the end of this chapter.

14. 14 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Utility and Consumer Decision Making Income effect The change in the quantity demanded of a good that results from the effect of a change in price on consumer purchasing power, holding all other factors constant. Substitution effect The change in the quantity demanded of a good that results from a change in price making the good more or less expensive relative to other goods, holding constant the effect of the price change on consumer purchasing power. The Income Effect and Substitution Effect of a Price Change Define utility and explain how consumers choose goods and services to maximize their utility. 9.1 LEARNING OBJECTIVE

15. 15 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Utility and Consumer Decision Making INCOME EFFECT SUBSTITUTION EFFECT PRICE DECREASE Increases the consumer‘s purchasing power, which... causes the quantity demanded to increase, if a normal good. causes the quantity demanded to decrease, if an inferior good, Lowers the opportunity cost of consuming the good, which causes the quantity of the good demanded to increase. PRICE INCREASE Decreases the consumer's purchasing power, which... causes the quantity demanded to decrease, if a normal good. causes the quantity demanded to increase, if an inferior good, Raises the opportunity cost of consuming the good, which causes the quantity of the good demanded to decrease. Table 9-4 Income Effect and Substitution Effect of a Price Change The Income Effect and Substitution Effect of a Price Change Define utility and explain how consumers choose goods and services to maximize their utility. 9.1 LEARNING OBJECTIVE

16. 16 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Utility and Consumer Decision Making NUMBER OF SLICES OF PIZZA MARGINAL UTILITY FROM LAST SLICE (MU PIZZA ) MARGINAL UTILITY PER DOLLAR NUMBER OF CUPS OF COKE MARGINAL UTILITY FROM LAST CUP (MU COKE ) MARGINAL UTILITY PER DOLLAR 12013.33120 21610.67215 3106.67310 464455 521.33533 6 33 –6 11 – Table 9-5 Adjusting Optimal Consumption to a Lower Price of Pizza The Income Effect and Substitution Effect of a Price Change Define utility and explain how consumers choose goods and services to maximize their utility. 9.1 LEARNING OBJECTIVE

17. 17 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Where Demand Curves Come From FIGURE 9-2 Deriving the Demand Curve for Pizza A consumer responds optimally to a fall in the price of a product by consuming more of that product. In panel (a), the price of pizza falls from $2 per slice to $1.50, and the optimal quantity of slices consumed rises from 3 to 4. When we graph this result in panel (b),we have the consumer’s demand curve. Use the concept of utility to explain the law of demand. 9.2 LEARNING OBJECTIVE

18. 18 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Where Demand Curves Come From FIGURE 9-3 Deriving the Market Demand Curve from Individual Demand Curves Use the concept of utility to explain the law of demand. 9.2 LEARNING OBJECTIVE The table shows that the total quantity demanded in a market is the sum of the quantities demanded by each buyer. We can find the market demand curve by adding horizontally the individual demand curves in parts (a), (b), and (c). For instance, at a price of $1.50, your quantity demanded is 4 slices, David’s quantity demanded is 6 slices, and Lori’s quantity demanded is 5 slices. Therefore, part (d) shows a price of $1.50, and a quantity demanded of 15 is a point on the market demand curve.

19. 19 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Social Influences on Decision Making The Effects of Celebrity Endorsements In many cases, it is not just the number of people who use a product that makes it desirable but the types of people who use it. If consumers believe that media stars or professional athletes use a product, demand for the product will often increase. Sociologists and anthropologists have argued that social factors such as culture, customs, and religion are very important in explaining the choices consumers make. Economists have traditionally seen such factors as being relatively unimportant, if they take them into consideration at all. Recently, however, some economists have begun to study how social factors influence consumer choice. Explain how social influences can affect consumption choices. 9.3 LEARNING OBJECTIVE

20. 20 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Are There Any Upward-Sloping Demand Curves in the Real World? Making the Connection For a demand curve to be upward sloping, the good would have to be an inferior good and the income effect would have to be larger than the substitution effect. Goods with upward-sloping demand curves, referred to as Giffen goods, are difficult to find. Explain how social influences can affect consumption choices. 9.3 LEARNING OBJECTIVE Rice is a Giffen good in poor parts of China. YOUR TURN: Test your understanding by doing related problem 2.7 at the end of this chapter.

21. 21 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Why Do Firms Pay Tiger Woods to Endorse Their Products? Making the Connection The average weekend golfer might believe that if Tiger endorses Nike golf balls, maybe Nike balls are better than other golf balls. But it seems more likely that people buy products associated with Tiger Woods or other celebrities because using these products makes them feel closer to the celebrity endorser or because it makes them appear to be fashionable. Explain how social influences can affect consumption choices. 9.3 LEARNING OBJECTIVE Tiger Woods earns much more from product endorsements than from playing golf. YOUR TURN: Test your understanding by doing related problem 3.9 at the end of this chapter.

22. 22 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Social Influences on Decision Making Network Externalities Network externality A situation in which the usefulness of a product increases with the number of consumers who use it. Does Fairness Matter? A Test of Fairness in the Economic Laboratory: The Ultimatum Game Experiment Economists have used experiments to increase their understanding of the role that fairness plays in consumer decision making. Explain how social influences can affect consumption choices. 9.3 LEARNING OBJECTIVE

23. 23 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Social Influences on Decision Making Does Fairness Matter? Business Implications of Fairness FIGURE 9-4 The Market for Tickets to The Producers Explain how social influences can affect consumption choices. 9.3 LEARNING OBJECTIVE The St. James Theater could have raised prices for the Broadway musical The Producers to $125 per ticket and still sold all of the 1,644 tickets available. Instead, the theater kept the price of tickets at $75, even though the result was a shortage of more than 400 seats. Is it possible that this strategy maximized profits?

24. 24 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Professor Krueger Goes to the Super Bowl Making the Connection Should the NFL raise the price of Super Bowl tickets? Explain how social influences can affect consumption choices. 9.3 LEARNING OBJECTIVE Krueger concluded that whatever the NFL might gain in the short run from raising ticket prices, it would more than lose in the long run by alienating football fans. YOUR TURN: Test your understanding by doing related problems 3.11 and 3.12 at the end of this chapter.

25. 25 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Behavioral Economics: Do People Make Their Choices Rationally? Behavioral economics The study of situations in which people make choices that do not appear to be economically rational. They take into account monetary costs but ignore nonmonetary opportunity costs. They fail to ignore sunk costs. They are unrealistic about their future behavior. Consumers commonly commit the following three mistakes when making decisions: Describe the behavioral economics approach to understanding decision making. 9.4 LEARNING OBJECTIVE

26. 26 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Behavioral Economics: Do People Make Their Choices Rationally? Ignoring Nonmonetary Opportunity Costs Opportunity cost The highest-valued alternative that must be given up to engage in an activity. Endowment effect The tendency of people to be unwilling to sell a good they already own even if they are offered a price that is greater than the price they would be willing to pay to buy the good if they didn’t already own it. Describe the behavioral economics approach to understanding decision making. 9.4 LEARNING OBJECTIVE

27. 27 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics A Blogger Who Understands the Importance of Ignoring Sunk Costs Making the Connection Would you give up being a surgeon to start your own blog? Describe the behavioral economics approach to understanding decision making. 9.4 LEARNING OBJECTIVE YOUR TURN: Test your understanding by doing related problems 4.7, 4.8, and 4.9 at the end of this chapter. Knowing that it is rational to ignore sunk costs can be important in making key decisions in life.

28. 28 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Behavioral Economics: Do People Make Their Choices Rationally? Failing to Ignore Sunk Costs Sunk cost A cost that has already been paid and cannot be recovered. Being Unrealistic about Future Behavior If you are unrealistic about your future behavior, you underestimate the costs of choices that you make today. Describe the behavioral economics approach to understanding decision making. 9.4 LEARNING OBJECTIVE

29. 29 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Why Don’t Students Study More? Making the Connection If the payoff to studying is so high, why don’t students study more? Describe the behavioral economics approach to understanding decision making. 9.4 LEARNING OBJECTIVE Many students study less than they would if they were more realistic about their future behavior. YOUR TURN: Test your understanding by doing related problems 4.10 and 4.11 at the end of this chapter.

30. 30 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Solved Problem 9-4 How Do You Get People to Save More of Their Income? Use your understanding of consumer decision making to show how a savings plan may work. Describe the behavioral economics approach to understanding decision making. 9.4 LEARNING OBJECTIVE YOUR TURN: For more practice, do related problems 4.12 and 4.13 at the end of this chapter.

31. 31 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics The Power of Oprah’s Kindle Endorsement >> AN INSIDE LOOK When successful, a celebrity endorsement can shift the demand curve for a product to the right, from D 1 to D 2.

32. 32 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Behavioral economics Budget constraint Endowment effect Income effect Law of diminishing marginal utility Marginal utility (MU) Network externality Opportunity cost Substitution effect Sunk cost Utility KEY TERMS

33. 33 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Appendix CONSUMPTION BUNDLE A CONSUMPTION BUNDLE B 2 slices of pizza and 1 can of Coke 1 slice of pizza and 2 cans of Coke We assume that the consumer will always be able to decide which of the following is true: The consumer prefers bundle A to bundle B. The consumer prefers bundle B to bundle A. The consumer is indifferent between bundle A and bundle B; that is, the consumer receives equal utility from the two bundles. Using Indifference Curves and Budget Lines to Understand Consumer Behavior Consumer Preferences Use indifference curves and budget lines to understand consumer behavior. LEARNING OBJECTIVE

34. 34 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Appendix Indifference Curves Indifference curve A curve that shows the combinations of consumption bundles that give the consumer the same utility. Consumer Preferences Use indifference curves and budget lines to understand consumer behavior. LEARNING OBJECTIVE

35. 35 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Appendix FIGURE 9A-1 Plotting Dave’s Preferences for Pizza and Coke Consumer Preferences Every possible combination of pizza and Coke will have an indifference curve passing through it, although in the graph we show just four of Dave’s indifference curves. Dave is indifferent among all the consumption bundles that are on the same indifference curve. So, he is indifferent among bundles E,B, and F because they all lie on indifference curve I 3. Moving to the upper right in the graph increases the quantities of both goods available for Dave to consume. Therefore, the further to the upper right the indifference curve is, the greater the utility Dave receives. Use indifference curves and budget lines to understand consumer behavior. LEARNING OBJECTIVE

36. 36 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Appendix Marginal rate of substitution (MRS) The rate at which a consumer would be willing to trade off one good for another. The Slope of an Indifference Curve Consumer Preferences Use indifference curves and budget lines to understand consumer behavior. LEARNING OBJECTIVE

37. 37 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Appendix Can Indifference Curves Ever Cross? Consumer Preferences FIGURE 9A-2 Indifference Curves Cannot Cross Because bundle X and bundle Z are both on indifference curve I 1, Dave must be indifferent between them. Similarly, because bundle X and bundle Y are on indifference curve I 2, Dave must be indifferent between them. The assumption of transitivity means that Dave should also be indifferent between bundle Z and bundle Y. We know that this is not true, however, because bundle Y contains more pizza and more Coke than bundle Z. So Dave will definitely prefer bundle Y to bundle Z, which violates the assumption of transitivity. Therefore, none of Dave’s indifference curves can cross. Use indifference curves and budget lines to understand consumer behavior. LEARNING OBJECTIVE

38. 38 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Appendix FIGURE 9A-3 Dave’s Budget Constraint The Budget Constraint Dave’s budget constraint shows the combinations of slices of pizza and cans of Coke he can buy with $10. The price of Coke is $1 per can, so if he spends all of his $10 on Coke, he can buy 10 cans (bundle G). The price of pizza is $2 per slice, so if he spends all of his $10 on pizza, he can buy 5 slices (bundle L). As he moves down his budget constraint from bundle G, he gives up 2 cans of Coke for every slice of pizza he buys. Any consumption bundles along the line or inside the line are affordable. Any bundles that lie outside the line are unaffordable. Use indifference curves and budget lines to understand consumer behavior. LEARNING OBJECTIVE

39. 39 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Appendix FIGURE 9A-4 Finding Optimal Consumption Choosing the Optimal Consumption of Pizza and Coke Dave would like to be on the highest possible indifference curve, but he cannot reach indifference curves such as I 4 that are outside his budget constraint. Dave’s optimal combination of slices of pizza and cans of Coke comes at point B, where his budget constraint just touches—or is tangent to—the highest indifference curve he can reach. At point B, he buys 3 slices of pizza and 4 cans of Coke. Use indifference curves and budget lines to understand consumer behavior. LEARNING OBJECTIVE

40. 40 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Dell Determines the Optimal Mix of Products Making the Connection Consumers in panel (a) of the figure prefer screen size to processor speed. Consumers in panel (b) prefer processor speed to screen size. YOUR TURN: Test your understanding by doing related problem 9A.8 at the end of this chapter. Use indifference curves and budget lines to understand consumer behavior. LEARNING OBJECTIVE

41. 41 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Appendix FIGURE 9A-5 How a Price Decrease Affects the Budget Constraint Choosing the Optimal Consumption of Pizza and Coke Deriving the Demand Curve A fall in the price of pizza from $2 per slice to $1 per slice increases the maximum number of slices Dave can buy with $10 from 5 to 10. The budget constraint rotates outward from point A to point B to show this. Use indifference curves and budget lines to understand consumer behavior. LEARNING OBJECTIVE

42. 42 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Appendix FIGURE 9A-6 How a Price Change Affects Optimal Consumption Choosing the Optimal Consumption of Pizza and Coke Deriving the Demand Curve In panel (a), a fall in the price of pizza results in Dave’s consuming less Coke and more pizza. 1. A fall in the price of pizza rotates the budget constraint outward because Dave can now buy more pizza with his $10. 2. In the new optimum on indifference curve I 2, Dave changes the quantities he consumes of both goods. His consumption of Coke falls from 4 cans to 3 cans. 3. In the new optimum, Dave’s consumption of pizza increases from 3 slices to 7 slices. In panel (b) Dave responds optimally to the fall in the price of pizza from $2 per slice to $1, by increasing the quantity of slices he consumes from 3 slices to 7 slices. When we graph this result, we have Dave’s demand curve for pizza. Use indifference curves and budget lines to understand consumer behavior. LEARNING OBJECTIVE

43. 43 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Appendix Solved Problem 9A-1 When Does a Price Change Make a Consumer Better Off? Because Dave can now reach a higher indifference curve, we can conclude that he is better off as a result of the price change. YOUR TURN: For more practice, do related problem 9A.10 at the end of this chapter. Use indifference curves and budget lines to understand consumer behavior. LEARNING OBJECTIVE

44. 44 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Appendix FIGURE 9A-7 Income and Substitution Effects of a Price Change Choosing the Optimal Consumption of Pizza and Coke The Income Effect and the Substitution Effect of a Price Change Following a decline in the price of pizza, Dave’s optimal consumption of pizza increases from 3 slices (point A) per week to 7 slices per week (point C). We can think of this movement from point A to point C as taking place in two steps: The movement from point A to point B along indifference curve I 1 represents the substitution effect, and the movement from point B to point C represents the income effect. Dave increases his consumption of pizza from 3 slices per week to 5 slices per week because of the substitution effect of a fall in the price of pizza and from 5 slices per week to 7 slices per week because of the income effect. Use indifference curves and budget lines to understand consumer behavior. LEARNING OBJECTIVE

45. 45 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Appendix FIGURE 9A-8 How a Change in Income Affects the Budget Constraint Choosing the Optimal Consumption of Pizza and Coke How a Change in Income Affects Optimal Consumption When the income Dave has to spend on pizza and Coke increases from $10 to $20, his budget constraint shifts outward. With $10, Dave could buy a maximum of 5 slices of pizza or 10 cans of Coke. With $20,he can buy a maximum of 10 slices of pizza or 20 cans of Coke. Use indifference curves and budget lines to understand consumer behavior. LEARNING OBJECTIVE

46. 46 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Appendix FIGURE 9A-9 How a Change in Income Affects Optimal Consumption Choosing the Optimal Consumption of Pizza and Coke How a Change in Income Affects Optimal Consumption An increase in income leads Dave to consume more Coke and more pizza. 1. An increase in income shifts Dave’s budget constraint outward because he can now buy more of both goods. 2. In the new optimum on indifference curve I 2, Dave changes the quantities he consumes of both goods. His consumption of Coke increases from 4 cans to 6 cans. 3. In the new optimum, Dave’s consumption of pizza increases from 3 slices to 7 slices. Use indifference curves and budget lines to understand consumer behavior. LEARNING OBJECTIVE

47. 47 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Appendix FIGURE 9A-10 At the Optimum Point, the Slopes of the Indifference Curve and Budget Constraint Are the Same The Slope of the Indifference Curve, the Slope of the Budget Line, and the Rule of Equal Marginal Utility per Dollar Spent At the point of optimal consumption, the marginal rate of substitution is equal to the ratio of the price of the product on the horizontal axis to the price of the product on the vertical axis. Use indifference curves and budget lines to understand consumer behavior. LEARNING OBJECTIVE

48. 48 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Appendix The Slope of the Indifference Curve, the Slope of the Budget Line, and the Rule of Equal Marginal Utility per Dollar Spent The Rule of Equal Marginal Utility per Dollar Spent Revisited From the equality above, we derive the optimal point of consumption: Use indifference curves and budget lines to understand consumer behavior. LEARNING OBJECTIVE

49. 49 of 49 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall · Economics · R. Glenn Hubbard, Anthony Patrick O’Brien, 3e. Chapter 9: Consumer Choice and Behavioral Economics Indifference curve Marginal rate of substitution (MRS) KEY TERMS