Solved Problem: Using the Demand and Supply Model to Analyze the Effects of a Tariff on Televisions

Supports: MicroeconomicsMacroeconomicsEconomics, and Essentials of Economics, Chapter 4, Section 4.4

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The model of demand and supply is useful in analyzing the effects of tariffs. In Chapter 9, Section 9.4 (Macroeconomics, Chapter 7, Section 7.4) we analyze the situation—for instance, the market for sugar—when U.S. demand is a small fraction of total world demand and when the U.S. both produces the good and imports it.

In this problem, we look at the television market and assume that no domestic firms make televisions. (A few U.S. firms assemble limited numbers of televisions from imported components.) As a result, the supply of televisions consists entirely of imports. Beginning in April, the Trump administration increased tariff rates on imports of televisions from Japan, South Korea, China, and other countries. Tariffs are effectively a tax on imports, so we can use the analysis in Chapter 4, Section 4.4, “The Economic Effect of Taxes” to analyze the effect of tariffs on the market for televisions.  

  1. Use a demand and supply graph to illustrate the effect of an increased tariff on imported televisions on the market for televisions in the United States. Be sure that your graph shows any shifts of the curves and the equilibrium price and quantity of televisions before and after the tariff increase.
  2. An article in the Wall Street Journal discussed the effect of tariffs on the market for used goods. Use a second demand and supply graph to show the effect of a tariff on imports of new televisions on the market in the United States for used televisions. Assume that no used televisions are imported and that the supply curve for used televisions is upward sloping.

Solving the Problem
Step 1: Review the chapter material. This problem is about the effect of a tariff on an imported good on the domestic market for the good. Because a tariff is a like a tax, you may want to review Chapter 4, Section 4.4, “The Economic Effect of Taxes.”

Step 2: Answer part a. by drawing a demand and supply graph of the market for televisions in the United States that illustrates the effect of an increased tariff on imported televisions.  The following figure shows that a tariff causes the supply curve of televisions to shift up from S1 to S2. As a result, the equilibrium price increases from P1 to P2, while the equilibrium quantity falls from Q1 to Q2.

Step 2: Answer part b. by drawing a demand and supply graph of the market for used televisions in the United States that illustrates the effect on that market of an increased tariff on imports of new televisions. Although the tariff on imported televisions doesn’t directly affect the market for used televisions, it does so indirectly. As the article from the Wall Street Journal notes, “Today, in the tariff era, demand for used goods is surging.” Because used televisions are substitutes for new televisions, we would expect that an increase in the price of new televisions would cause the demand curve for used televisions to shift to the right, as shown in the following figure. The result will be that the equilibrium price of used televisions will increase from P1 to P2, while the equilibrium quantity of used televisions will increase from Q1 to Q2.

To summarize: A tariff on imports of new televisions increases the price of both new and used televisions. It decreases the quantity of new televisions sold but increases the quantity of used televisions sold.

Solved Problem: Do Dating Apps Have a Principal-Agent Problem?

Supports: Macroeconomics, Chapter 5, Section 5.3 or Chapter 6, Section 6.1; Microeconomics and Economics, Chapter 7, Section 7.3 or Chapter 8, Section 8.1.

Image from Reuters via the Wall Street Journal.

A recent paper by Iyah Rahwan, of the Max Planck Institute for Human Development in Berlin Germany, and colleagues raises the possibility that dating apps, like Tinder, OkCupid, and Bumble, may have a principal-agent problem. Dating apps—like nearly all other subscription apps—generate more income if subscribers pay for the app over a longer period of time. Many people use dating apps in the hope of connecting with another app user with whom they can have a long-term relationship.

a. What is the principal-agent problem?

b. Explain whether dating apps may have a principal-agent problem. If they do, who is the principal and who is the agent?

c. How does your answer to part b. affect your estimate of how likely people using dating apps are to find a long-term relationship using these apps?

Solving the Problem

Step 1:  Review the chapter material. This problem is about the principal-agent problem, so you may want to review either of the two sections in which the principal-agent problem is discussed:  Macroeconomics, Chapter 5, Section 5.3, “Information Problems and Externalities in the Market for Health Care” or Chapter 6, Section 6.1, “Types of Firms” (Microeconomics and Economics, Chapter 7, Section 7.3 or Chapter 8, Section 8.1.)

Step 2: Answer part a. by defining “principal-agent” problem. Principal-agent is defined in the textbook this way: A problem caused by an agent pursuing the agent’s own interests rather than the interests of the principal who hired the agent.

Step 3: Answer part b. by explaining why dating apps may have a principal-agent problem and by identifying who is the principal and who is the agent in this situation. With dating apps, the principal is the app user who, typically, uses the app to help find a partner for a long-term relationship. The owners of the dating app are the agent because they have been hired by the app user to help the user achieve the goal of starting a long-term relationship. Unfortunately, the owners of the dating app have a different goal than does the app user. The goal of the owners is to have users keep subscribing to the app. Anyone who finds a long-term relationship using the app is likely (we hope!) to drop his or her subscription to the app. Therefore, whereas the app user would like to quickly find a partner for a long-term relationship, the owners of the app want the app user to take a long time to find such a partner.

Step 4: Answer part c. by discussing how the principal-agent problem may affect the likelihood of someone using a dating app successfully finding someone for a long-term relationship. The answer to part b. indicates that dating apps may have an incentive to make it somewhat more difficult to find a long-term relationship using the app—perhaps by employing a matching algorithm that doesn’t result in users easily finding good matches. Therefore, it’s likely that the principal-agent problem make it less likely that people using dating apps will successfully find a partner for a long-term relationship.

Source: Iyah Rahwan, et al., “Price of Anarchy in Algorithmic Matching of Romantic Partners,”  ACM Transactions on Economics and Computation, Vol. 12, No. 1, pp. 1-25.

H/T Nicholas Christakis on X.