Aug 14 2015

## Marketplace explains: floating versus managed exchange rate systems

For years China has kept the value of its currency, the yuan, artificially low in order to help exporters, much to the annoyance of the countries trading partners. European and American trade authorities have called for China to abandon its managed exchange rate system, hoping that a stronger yuan would help their own manufacturers as consumers would demand less of the undervalued Chinese goods.

We’ll, this week China has begun to relax its exchange rate controls, but to the frustration of Western trade promoters, the currency has moved in the wrong direction, actually weakening against the dollar and euro.

Marketplace explains the differences between floating and managed exchange rates in the podcast below.

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Nov 27 2014

## A mathematical proof of the Marshall Lerner Condition

One of the toughest topics to teach in IB higher level Economics is the Marshall Lerner Condition, which is an International Economics concept which states the following:

If the combined price elasticities of demand of a nation’s imports and exports is greater than one (PEDx + PEDm > 1), then a depreciation or a devaluation of the nation’s currency will move its current account balance towards surplus.

This is a concept I have been teaching for eight years now, and I have even written about it in my textbook and produced a YouTube video lecture explaining it to students, but one thing I’ve never done is attempted a mathematical proof of the concept (needless to say, I avoid using math as much as possible, and the prospect of “proving” the MLC was always too daunting).

But this evening I received an email from an Economics teacher in Paris asking for just such a proof. So I buckled down and worked it out. In her email, the teacher said:

The Marshall Lerner Condition states that if the PEDx + PEDm > 1 then a depreciation in a country’s currency will reduce a current account deficit.

Suppose the PED for exports = .6 and the PED for imports = .5. The sum is greater than 1, therefore the MLC is met. A depreciation of this country’s currency should therefore improve its current account balance.

But based on my analysis, this country’s current account should be getting worse, not better.

For Exports: price is decreasing but the quantity demanded is increasing by proportionally  less (since PEDx = 0.6) so the country’s total export revenue is decreasing

For Imports: price is increasing and quantity demanded is decreasing by proportionally less (since PEDm = 0.5) so the country’s total spending on imports is increasing

The country’s revenues from exports are decreasing while the country’s spending on imports are increasing, so overall the trade balance is getting worse (moving deeper into deficit) not improving.

What am I doing wrong?

This teacher’s email really stumped me at first, because her logic is totally sound. I figured the only way I was going to be satisfied was if I worked it mathematically. So here’s the result and the reply I sent to the teacher:

Hello,

Your email really got me thinking about this. Your logic stumped me at first, but then inspired me to go work it out with numbers. So, hopefully my “proof” of the MLC below will clarify your confusion.

To simplify the analysis we will use easy numbers. I will use your values of PEDx = 0.6 and PEDm = 0.5

Assumptions:

• The US and Canada are trading partners
• Current exchange rate: \$1 US = \$1 CA
• US exports 10 widgets at \$1 US apiece for a total export revenue of \$10 US
• US imports 10 wingdings at \$1 CA apiece for a total import expenditure of \$10 US
• US trade balance: \$10 – \$10 = 0
• PEDx = 0.6 and PEDm = 0.5

Next, assume the US \$ depreciates by 10% against the CA \$. Now,

• \$1 US = \$0.90 CA
• \$1 CA = \$1.11 US

Impact on imports:

• Price to Americans of Canadian wingdings rises to \$1.11 US
• Quantity demanded falls by 5.5% to 9.45
• Total expenditures on Canadian imports expressed in US \$: \$1.11 x 9.45 = \$10.49

In order for the US trade balance to improve US export revenues must increase by more than \$0.49 US.

Impact on exports:

• Price to Canadians of US widgets falls by 10% to \$0.90 CA
• Quantity demanded increases by 6% to 10.6
• Total revenue from exports to Canada expressed in CA \$: \$0.90 x 10.6 = \$9.54 CA.
• Since \$1 CA = \$1.11 US, the value of US exports to Canada expressed in US \$ is \$9.54 x \$1.11 = \$10.59

Expressed in US \$, exports increased by \$0.59 and imports increased by \$0.49.

Therefore, US net exports are now \$10.59 – \$10.49 = \$0.1. The MLC is met and the US trade balance moves into surplus.

I think the only mistake with the logic you applied in your email was that you were not considering that a country’s balance of trade is measured in its own home currency. As you can see, if we measured the value of US exports in Canadian dollars, then following the depreciation of the US dollar American export revenues actually appear to decrease, moving the US into a current account deficit. But even though Canadians are spending less of their own dollars on US goods, the Canadian dollar has now appreciated by 11%, therefore the value of US exports expressed in US \$ actually increases (due to the now weaker US dollar)!

I hope this all makes sense! Thanks for inspiring me to buckle down and tackle this analysis! I’ve been teaching this concept for eight years and have never actually taken the time to walk through a proof like this.

Best,
Jason

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Nov 17 2014

## Current Account Balance analysis and questions

The table below shows the trade balances for the nations from which my year two IB Economics student come. They are ranked in order from the country whose trade deficit makes up the largest percentage of its GDP  to the country whose trade surplus makes up the largest percentage of its GDP. The blue bars represent the value of the deficit or surplus of each nation. As can be seen, Zimbabwe’s trade deficit is very small in dollar terms, but since its economy is also very small this deficit makes up a large percentage of its total GDP. Click on the image to visit an interactive version of the chart on which you can study the data more closely. Then answer the questions that follow.

Discussion Questions:

1. Identify and define the four components of a nation’s current account balance.
2. According to the data, which three countries are the most import dependent? Which three countries are the most export dependent? Which country has the most balance trade in goods and services? Which has the most imbalanced trade?
3. For one of deficit countries above, answer the following two questions:
1. Assuming its currencies’ exchange rates is floating, explain how persistent current account deficits will affect a country’s exchange rate over time?
2. Summarize and explain the likely effects of a current account deficit on the following: a) the financial account balance, b) domestic interest rates, and c) national debt.
4. For one of the surplus countries above, answer the following two questions:
1. Assuming its currencies’ exchange rates is floating, explain how persistent current account surpluses will affect a country’s exchange rate over time?
2. Summarize and explain the likely effects of a current account surplus on the following: a) domestic savings rates, b) the financial account balance.
5. What are the various methods a country can take to reduce a current account deficit? What is the benefit of having a balanced current account as opposed to a large deficit or surplus?

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Dec 04 2013

## Planet Money’s t-shirt, comparative advantage and protectionism. A lesson in International Trade

A while back the team behind my favorite podcast, Planet Money, decided to make a t-shirt. In the process, they would tell the whole story of how a t-shirt is made in our global economy. They would track the production of the shirt from the fields where the cotton was grown to the plant where it was spun into thread to the factory where the cloth was cut and stitched into a finished t-shirt.

To finance the story, the Planet Money team undertook a Kickstarter crowd-financing campaign, hoping to get 4,000 listeners like myself to contribute \$25 each to help pay for the production of the shirt and the reporting of said production. In the end, over 25,000 listeners supported the campaign, raising nearly \$600,000 for the team to pursue its dream of making and telling the whole story behind it!

Along the way they’ve told many great stories about the people and resources that have gone into their shirt, and just this week they released an interactive documentary about the whole project, start to finish. On Sunday evening, after experiencing the documentary, I was inspire to create a lesson for my year 2 IB Economics students, who happen to be studying International Trade (section 3 of the IB course), at this very moment. Below is that lesson, which they are working on this week.

Introduction: The purpose of this activity is to reflect on the principle of comparative advantage and better understand how the patterns of global trade are shaped by this fundamental concept. You will watch and read the story of a t-shirt that was manufactured using resources from four separate countries. Next, you will respond to an essay prompt. Your answer will be graded as a minor assessment.

Steps:

1. Read the page that tells the backstory to the Planet Money t-shirt project.
2. Watch the five part documentary as a class
3. Read the stories behind the t-shirt’s different stages of production:

Respond to the essay prompt below. (You may begin working on your response while reading the pages above). Your response is due at the beginning of next class and will be graded as a “minor assessment”.

Essay prompt:

A comparative advantage exists when a particular task can be done or a good can be produced at a lower opportunity cost by one nation than by a potential trading partner. When countries specialize in the goods for which they have a comparative advantage, the allocation of resources (land, labor and capital) between nations is more efficient, allowing for a greater level of overall production and income than what is possible without trade.

Carefully explain how the the story of the production of the Planet Money t-shirt demonstrates the principle of comparative advantage. (450 words maximum)

Bonus readingProtectionism and the Planet Money t-shirt

In the above post on the Planet Money blog (made December 2), we learn about the impact that tariffs had on the production of the Planet Money t-shirt.

As you saw in the documentary, the men’s shirt was made in Bangladesh, while the women’s was made in Columbia. We also learned that the Columbian textile worker earn about 3 times as much as the Bangladeshi workers. Why, you may ask, didn’t the ladies’ shirts get made in Bangladesh too? The answer has to do with two “P’s”: productivity and protectionism.

First productivity: According to this podcast, from a week ago, in the Bangladeshi factory where the men’s t-shirt was made, 32 workers on an assembly line would produce 80 t-shirts per hour. In Columbia, on the other hand, 8 workers could produce 140 t-shirts per hour. A simple calculation reveals that the productivity, measured in t-shirts per hour per worker, in the two countries is:

• Bangladesh: 80/32 = 2.5 t-shirts per hour per worker
• Columbia: 140/8 = 17.5 t-shirts per hour per worker

The Columbian workers, despite being paid three times the monthly wage that Bangladeshis are making, are 7 times more productive. What accounts for this productivity? Generally, increased productivity is the result of the integration of better or more technology and better training or education among workers. In a low-skilled manufacturing industry like garments, the greater productivity is almost certainly due to greater access to technology in Columbia than in Bangladesh.

On to the second “P”, protectionism: According to this post, due to Columbia’s free trade agreement with the United States, textiles, and most other goods, can be imported into the US “duty-free”, meaning there are no tariffs (import taxes) imposed on Columbian produced goods. This compares to textiles from Bangladesh, on which a 16% tariff is imposed, adding significantly to the cost of producing goods there.

So, let’s put all this together and weigh the advantages and disadvantages of producing t-shirts in the two countries:

In Bangladesh:

• Advantages: Low wages
• Disadvantages: Low productivity and a 16% tariff

In Columbia:

• Advantages: High productivity and “duty-free” imports
• Disadvantages: High wages

Ironically, while Columbia enjoys certain advantages as a trade partner with the US with high productivity, it appears that the garment industry is slowly disappearing there, as economic development and growth drives up the wage rate further, leading to the country losing its comparative advantage in textile production. Even duty-free status with the US may not allow Columbia to continue to produce t-shirts in the future, as the lower wages of even less developed countries like Cambodia, Laos and yes, even Bangladesh, are too tempting for the garment industry to resist.

Feb 07 2013

## Lesson plan: Elasticity, exchange rates and the balance of payments – understanding the Marshall Lerner Condition

Related Unit: IB Economics Unit 4.7 – Balance of Payments (Unit 3.3 in the new IB Economics syllabus)

Topic: The Marshall Lerner Condition and the J-Curve

Learning Goals/Objectives:

• For students to understand that the levels of price elasticity of demand for a country’s imports and exports determines whether a depreciation or devaluation of the country’s currency will move the nation’s balance of payments towards a surplus or a deficit.
• For students to understand the impact of time on the effect of a depreciation or devaluation of a nation’s currency on its balance of payments in the current account.
• For students to evaluate the argument that a country will always benefit from a weaker currency.

Test of prior knowledge:

1. Define ‘price elasticity of demand’ and explain how it is measured.
2. With the use of examples, explain why some products have low price elasticity while others have a high elasticity. With the use of examples, explain why the price elasticity of demand for some goods changes over time
3. Explain how the depreciation of a country’s exchange rate might affect its current account balance. IS THIS ALWAYS THE CASE?
4. How might the PED for exports and imports influence the balance on the current account following a change in the value of a nation’s currency?

Part 1:

The exchange rate of Japanese Yen in the United States over the last two years:

Take a snapshot of your two-year exchange rate diagram in OneNote, then copy and paste the questions below into the page.

Questions to answer in OneNote:

1. Write a brief description of the changes in your country’s exchange rate over the last two years. (2 marks)
2. Focus on two specific time periods from during the last two years: One in which your currency appreciated noticeably and one in which it depreciated noticeably. These could be periods of just a couple of days or longer periods of weeks or more. Highlight these in two different covers in your graph.
3. Describe what is happening to your currency during the two time periods you highlighted in your chart. (2 marks)
4. Explain TWO factors that may have caused the currency to change in value. (2 marks)
5. Given the changes to the exchange rate you identified above, what would you predict would happen to your country’s current account balance over the two periods identified? Explain. Following appreciation – in the short-run and in the long-runFollowing depreciation – in the short-run and in the long-run. (4 marks)
6. Why does the price elasticity of demand for imports and exports increase over time following a change in a country’s exchange rate? (2 marks)
7. Draw a J-Curve showing the likely change in your nation’s current account balance following the period of depreciation of its currency shown in your chart above and explain its shape, referring to your country’s currency. (2 marks)
8. For both the period of appreciation and the period of depreciation you identified above, explain the impact of the change in exchange rates on the following (4 marks)
• a firm that imports its raw materials from the other country
• a firm that exports its finished products to the other country
• consumers who buy imports from the other country
• a firm that produces good for the domestic market and competes with firms from the other country

Part 2:

Read the following article:  . Based on the extracts below, answer the questions that follow.

Some applaud the dollar’s fall because they believe it makes U.S. exports less expensive and that higher demand will cut the trade deficit. The downside of a low-value dollar is that it makes all the imports we consume more expensive, including raw material and parts used by U.S. businesses, and makes it costlier for U.S. dollar holders to travel or invest outside the U.S. A continued drop in the dollar’s value could destabilize the international economy, leading to a worldwide recession.

• Why might the weaker dollar worsen the US trade deficit? Under what conditions would the weaker dollar improve America’s trade deficit? (2 marks)

Some argue our large trade deficit (or current account deficit) is responsible for the fall in the dollar’s value. They have it backward. It is the flow of foreign investment dollars (the capital account) into the U.S. economy that drives the trade deficit.

• How does a large financial (capital) account surplus allow the United States to maintain a large current account deficit? (2 marks)

The world now is actually on a two-currency standard — the dollar and the euro. China in effect has fixed its currency to the dollar for the last two decades, and the Japanese central bank only allows the yen to fluctuate within a limited range against the dollar.

• How do exchange rate controls by China and Japan reduce the likelihood that a weaker dollar will improve the United States’ current account balance? (2 marks)

So long as the U.S. continues to offer a higher return on capital than its foreign competitors, both foreign banks’ and private investors’ demand for dollars grow, and the current account deficit can be sustained.

• If investments in the United States began earning lower returns relative to investments in other countries’ financial and capital markets, what would ultimately happen to the US balance of payments in its current and financial accounts? Explain (2 marks)

The above lesson was inspired by the Biz-Ed activity “International Trade: The Falling Dollar or Rising Pound?”

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