Aug 18 2014

Welcome all new Econ students! Time to start thinking like economists

One of the questions I like to ask my student during the first week of class every year is “What is Economics?” The answers are always interesting to read, because unlike many other high school classes, Econ is one of those subjects students sometimes have no idea what it’s all about when they sign up for the class. Below are some of the definitions of “Economics” students shared in their first day survey this week:
  • “Economics is the study of money flow between either countries or individual companies.”
  • “My definition of Economics is the control of money by a person, organization or nation.”
  • “Economics is a complex system that determines and justifies global prices, currency values, and ultimately the success of a nation.”
  • “I’d say Economics is the study of how humans use resources including income, investments, taxes and the economy.”
  • “I think economics is the study of investments and money. Especially income and outcome, and taxes in the government.”
  • “The study of the distribution of wealth and how human beings tend to handle wealth.”
  • “A bunch of old men moaning about all of the potentially free lunch oppurtunities they had missed in their youth, passed off as the behaviour of markets.”

As you can see, most students do not yet have a clear definition of the subject in their heads when they start the course, which is perfectly understandable! So I thought I’d start the year off by sharing my definition of economics. Please read the following introduction to Economics then answer the discussion question that follows.

So what IS Economics, anyway? Well, look around you. What do you see? From here in my classroom at Zurich International School, I see five new condominium buildings being built. I can count eight yellow cranes swinging their arms hauling construction materials around their respective sites. Beyond the cranes I see a beautiful forest stretching up a hillside with green sheep pastures and quaint farm houses scattered here and there. I see a church steeple and the rooftops of the businesses down in the village below school. I can just see the tops of cars racing along the A3 highway to and from Zurich and the other cities of central and eastern Switzerland.

Now ask yourself, how did things get to be this way? Why are new condos going up in the midst of Europe’s deepest recession in decades? Why are farmers still able to graze sheep on hillsides when 100 square meter condos are selling for a million francs just below their fields? Why are the ancient forests of the Sihlwald still standing even as development has encroached into most of the region’s  forests and natural ecosystems? How do normal people make enough money to live comfortably in this expensive country? Where do the things we buy come from? Who built this computer I’m typing on and what will I be doing for a living in twenty years?

One of my favorite quotes that to me sums up what economics is all about comes not from an economist, but from the civil rights leader Martin Luther King. In 1967 King wrote:

Did you ever stop to think that you can’t leave for your job in the morning without being dependent on most of the world? You get up in the morning and go to the bathroom and reach over for the sponge, and that’s handed to you by a Pacific islander. You reach for a bar of soap, and that’s given to you at the hands of a Frenchman. And then you go into the kitchen to drink your coffee for the morning, and that’s poured into your cup by a South American. And maybe you want tea: that’s poured into your cup by a Chinese. Or maybe you’re desirous of having cocoa for breakfast, and that’s poured into your cup by a West African. And then you reach over for your toast, and that’s given to you at the hands of an English-speaking farmer, not to mention the baker. And before you finish eating breakfast in the morning, you’ve depended on more than half the world. This is the way our universe is structured, this is its interrelated quality.

Economics is about all the questions I posed above and it’s about all the interactions King describes. Economics is about solving one major problem faced by all human societies going back thousands of years. Economics is about the problem of scarcity. Scarcity is the natural phenomenon arising from the fact that all the world’s resources are physically limited in quantity.

Limited resources alone would not pose a problem if it were not for one characteristics of human beings that makes us truly unique in the animal kingdom. The fact that we have desires and wants beyond our basic physical needs. In the face of humans’ practically unlimited desires and wants, the limited nature of the earth’s limited natural resources gives rise to conflicts regarding the allocation of those resources. Economics is the social science that deals with the allocation of earth’s scarce resources among the competing wants and needs of society. Economists provides society with various tools and techniques for efficiently allocating our scarce resources.

Discussion question:

  1. Scarcity of resources has given rise to countless conflicts among and between societies throughout history. Identify one conflict from the past or present that you think the problem of scarcity gave rise to.
  2. Some say that many of the environmental problems our world faces to day can be solved by economics. If that’s the case, then they must have to do with scarcity. Identify one environmental problem and explain how it relates to scarcity.
  3. Time is one of the scarcest resources. Explain how the decisions you make regarding your limited time in and out of school can be considered economic decisions.


94 responses so far

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.


  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.

3 responses so far

Nov 25 2013

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:


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


  • 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 following the depreciation in Canadian dollars, the export revenues actually decreased following the depreciation of the US $, 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 $)!

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.


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Apr 30 2013

The winners and losers of protectionism – the US sugar industry

Episode 454: The Lollipop War : Planet Money : NPR

This episode of my favorite podcast, Planet Money provides a great overview of the effects of the US government’s long-time protectiono f the sugar industry on various stakeholders.

When teaching the effects of protectionism, I urge students to evaluate its effects on both consumers and producers. Often, however, students generalize this analysis, and make broad statements like “consumer will pay higher prices for the good”, without clarifying who, exactly, the consumers of the protected good are. In the case of agricultural commodities, the “consumer” is typically not a private individual who buys the product at a store, rather, it’s the producers of process foods that use the commodities as inputs into their products which then are sold to consumers.

This is all to say that there is more than just a loss of “consumer surplus” in the market for a protected agricultural commodity. Rather, the effects can be far more serious, as the producers of hte consumer goods that use the commodity as an input may be forced to shut down their domestic production and move overseas. This is the story told in the podcast, as the maker of the candy dum dums has moved its plants to Mexico to take advantage not of lower wages or less regulation, rather the cheaper sugar that can be acquired there.

Listen to the podcast, and respond to the discussion questions that follow:

Discussion Questions:

  1. What method does the US government use to protect domestic sugar producers?
  2. What are the main economic arguments for continued protection of the US sugar industry?
  3. What are the main arguments for the removal of protection of US sugar producers?

2 responses so far

Apr 30 2013

“How to” succeed on IB Economics higher level paper 3

Published by under IB Economics

With the Econ exam just two days away, many students out there are wondering what to expect on the new higher level paper 3, the “quantitative methods” paper. I put this post together to share my own understanding of all the calculations students may be asked to do on this section of the exam.

First, let’s review the command terms you can expect to encounter on HL paper 3, and look at what is expected of students in questions of each type.

Command terms to expect on paper 3:

  • Calculate: “Obtain a numerical answer showing the relevant stages in the working.”
  • Construct: “Display information in a diagrammatic or logical form.”
  • Derive: “Manipulate a mathematical relationship to give a new equation or relationship.”
  • Determine: “Obtain the only possible answer.”
  • Draw: “Represent by means of a labelled, accurate diagram or graph, using a pencil. A ruler (straight edge) should be used for straight lines. Diagrams should be drawn to scale. Graphs should have points correctly plotted (if appropriate) and joined in a straight line or smooth curve.
  • Identify: “Provide an answer from a number of possibilities.”
  • Label: “Add labels to a diagram.”
  • Plot: “Mark the position of points on a diagram.”
  • Show: “Give the steps in a calculation or derivation.”
  • Show that: “Obtain the required result (possibly using information given) without the formality of proof. “Show that” questions do not generally require the use of a calculator.”
  • Sketch: “Represent by means of a diagram or graph (labelled as appropriate). The sketch should give a general idea of the required shape or relationship, and should include relevant features.”
  • Solve: “Obtain the answer(s) using algebraic and/or numerical and/or graphical methods.”

Calculations you may be required to make:

Section 1 Microeconomics

1.1 Markets


1. Explain a demand function (equation) of the form Qd = a – bP.
2. Plot a demand curve from a linear function (eg. Qd = 60 – 5P).
3. Identify the slope of the demand curve as the slope of the demand function Qd = a – bP, that is –b (the coefficient of P).
4. Outline why, if the “a” term changes, there will be a shift of the demand curve.
5. Outline how a change in “b” affects the steepness of the demand curve.

1. Explain a supply function (equation) of the form Qs = c + dP.
2. Plot a supply curve from a linear function (eg, Qs = –30 + 20 P).
3. Identify the slope of the supply curve as the slope of the supply function Qs = c + dP, that is d (the coefficient of P).
4. Outline why, if the “c” term changes, there will be a shift of the supply curve.
5. Outline how a change in “d” affects the steepness of the supply curve.

1. Calculate the equilibrium price and equilibrium quantity from linear demand and supply functions.

HOW TO: Set the demand and supply equations equal to one another and solve for P. Once you know the equilibrium price, plug it into either equation to find the quantity.

2. Plot demand and supply curves from linear functions, and identify the equilibrium price and equilibrium quantity.

Find the q-intercept of demand (this is the ‘a’ variable)
Find the p-intercept of both demand and supply (set Q = 0 and solve for P in both equations)
Draw the demand curve by connecting the q-intercept and the p-intercept of demand
Find the equilibrium price
Plot the supply curve by connecting the p-intercept of supply and the equilibrium price.
Draw dotted lines over to the equilibrium price and down to the equilibrium quantity.

3. State the quantity of excess demand or excess supply in the above diagrams.

HOW TO: There will only be an excess demand or supply if the question asks how a price OTHER THAN the equilibrium would affect the market. See the section on price controls below for more.

1.2 Elasticities:
1. Calculate PED using the following equation: PED=% change in Qd% change in P
2. Calculate PED between two designated points on a demand curve using the PED equation above.
3. Calculate XED using the following equation: XED = % change in Qd of good X% change in price of good Y
4. Calculate YED using the following equation: YED=% change in Qd% change in income
5. Calculate PES using the following equation: PES=% change in Qs% change in price

1.3 Government Intervention

1. Plot demand and supply curves for a product from linear functions and then illustrate the effects of a specific tax.
2. Calculate the effects of the imposition of a specific tax on the market (on price, quantity, consumer expenditure, producer revenue, government revenue, consumer surplus and producer surplus).

HOW TO: A tax takes money AWAY from the seller of a product. So to caclulate the effect of the tax in a supply equation you must subtract the amount of the tax from the price the seller receives.

For example: assume the supply of pencils is represented by Qs = -10 + 3P, and a $2 per unit tax is places on pencils. The new supply equation is: Qs = -10 + 3(P-2). Simplified, this gives us Qs = -16 + 3P. This is the new supply equation. Graphically, the supply curve has shifted leftwards by 6 units, or “upwards” by $2.

1. Plot demand and supply curves for a product from linear functions and then illustrate and/or calculate the effects of the provision of a subsidy on the market (on price, quantity, consumer expenditure, producer revenue, government expenditure, consumer surplus and producer surplus).

HOW TO: A subsidy is like a “tax in reverse”. It is a payment to the seller ABOVE what consumers pay, so it’s added to the price in the supply equation.

Assume pencil producers receive a $2 subsidy per pencil. With an original supply equation of Qs = -10 + 3P, the new supply is: -10 + 3(P+2). Simplified, this gives us Qs = -4+3P. The supply curve has shifted rightward by 6 units, or down by $2.

Price controls:
1. Calculate possible effects from the price ceiling diagram, including the resulting shortage and the change in consumer expenditure (which is equal to the change in firm revenue).
2. Calculate possible effects from the price floor diagram, including the resulting surplus, the change in consumer expenditure, the change in producer revenue, and government expenditure to purchase the surplus.

HOW TO: Simply plug the price floor or ceiling into the demand and supply equations to find the quantities that would be supplied and demanded. If there’s an effective price floor, the Qs should be greater than the Qd, meaning there’s a surplus. If there’s a price ceiling, Qd should be greater than Qs, meaning there’s a shortage.

1.5 Theory of the Firm

1. Calculate total, average and marginal product from a set of data and/or diagrams.

HOW TO: Total product is the output of workers as the number of workers increases.

Average product is the “output per worker” = TP/# of workers

Marginal product is the “output of the last worker” = Change in total product / change in the number of workers.

2. Calculate total fixed costs, total variable costs, total costs, average fixed costs, average variable costs, average total costs and marginal costs from a set of data and/or diagrams.

HOW TO: TFC is constant as output increases. It is the firm’s total cost when output = 0.

TVC increases as output increase, at first at a decreasing rate (due to increasing returns), and then at an increasing rate (due to diminishing marginal returns).

TC = TVC + TFC. If you know the firm’s fixed costs and its variable costs, TC can easily be calculated.

AFC = TFC / Q of output. AFC falls as output increases as the firm “spreads its overhead”. Graphically, it is the distance between AVC and ATC.

AVC = TVC / Quantity of output. AVC falls at first due to increasing returns and then increases due to diminishing returns. MC and AVC should intersect at the lowest point of AVC

ATC = AFC + AVC, or TC / Quantity of output. ATC lies ABOVE the AVC curve (since it includes the average fixed costs), and will intersect MC at its lowest pont.

MC = the change in TC / the change in output. It is the cost of the last unit produced. MC sloped down when a firm’s workers experience increasing returns and upwards once the firm experiences diminishing marginal returns.

1. Calculate total revenue, average revenue and marginal revenue from a set of data and/or diagrams.

HOW TO: Total revenue (TR) = price X quantity.

Average revenue (AR) is simply the price of the good. The demand curve can be labelled “D=AR=P” to help you remember this.

Marginal revenue (MR) = the change in total revenue divided by the change in quantity. This is the change in total revenue resulting from the last unit sold. For a PC firm, MR is constant and equal to the market price (since the firm is a price taker and can sell additional units for the same price.) But for an imperfectly competitive firm, MR is lower than price beyond the first unit of output, since the firm must lower its price to sell additional units of output. MR fall twice as steeply as the D=AR=P curve in an imperfect competitor diagram.

1. Calculate different profit levels from a set of data and/or diagrams.

HOW TO: Economic profit is usually found by the following equation. Profit = (P-ATC)Q. Find the per-unit profit (P-ATC) and multiply it by the quantity of output (Q).

If you are given total revenue (TR) and total cost (TC) data, than economic profit = TR-TC.

If ATC>P or if TC>TR, then the firm’s profit is negative, and it is earning losses.

Perfect Competition:
1. Calculate the short run shutdown price and the breakeven price from a set of data

HOW TO: A firm should shut down if the price in the market is lower than the firm’s minimum average variable cost. At this point, the firm’s total losses are greater than its total fixed costs, so it will LOSE LESS by shutting down!

A firm will break even when the price in the market equals the firm’s minimum ATC, or if the TR = TC (see above). Economic profits = 0.

1. Calculate from a set of data and/or diagrams the revenue maximizing level of output.

HOW TO: Total revenue is maximized when MR=0. If you have a table you can calculate the change in TR at each level of output, and when this equals zero, the firm would be maximizing its total revenues. Anything beyond this level of output, MR will be negative and the firm’s revenues will begin to fall.

Section 2 Macroeconomics

2.1 GDP
1. Calculate nominal GDP from sets of national income data, using the expenditure approach.

HOW TO: Nominal GDP is the quantity of output in a particular year multiplied by the prices in that year.

2. Calculate GNP/GNI from data

HOW TO: The difference between GDP and GNP is that you must SUBTRACT the value of output produced in a nation by companies based in other nations, but you must ADD the value of output produced in other nations by companies based in the nation you are calculating GNP for.

3. Calculate real GDP, using a price deflator.

HOW TO: Real GDP is the value of a nation’s output in a particular year measured using the prices from a base year. So you must multiply the quantity from the year in question by the prices from the base year (which should be provided).

If you are not given price and quantity data, rather you are given the GDP deflator price index, you can divide the nominal GDP for a particular by the GDP deflator for that year, and multiply by 100 to get the real GDP.

If you know the nominal GDP and the real GDP and are asked to calculate the GDP deflator, you simply divide the nominal by the real and multiply by 100.

If you have two years’ GDP deflators, and are asked to calculate the inflation between those years, you simply find the percentage change in the GDP deflator price indexes between the years given.

2.2 AD/AS
1. Calculate the multiplier using either of the following formulae: k=11-MPC or 1MRl=(MPS+MRT+MPM)
2. Use the multiplier to calculate the effect on GDP of a change in an injection in investment, government spending or exports.

HOW TO: If you know the MPC, you can estimate the effect of any change in spending in the economy on total GDP. For example. Assume the MPC = 0.8 and Net exports increase by $100 million. Calculate the total change in GDP.

k = 1/(1-0.8) = 5.

Now multiply the change in net exports by the multiplier: $100 million X 5 = $500 million
GDP will increase by $500 million as a result of the increase in net exports of $100 million.

2.3 Macroeconomic Objectives
1. Calculate the unemployment rate from a set of data.

HOW TO: The unemployment rate is the proportion of the labor force that is unemployed. This means they are actively seeking work but unable to find it.

You may be given a table showing the number of people in different groups, like college students, retirees, people looking for jobs, people who have given up looking for jobs, part time workers, full time workers, etc… You will have to calculate the unemployment rate from this information.

NOTE: People who are working part time but want to work full time ARE EMPLOYED. People who have given up looking for jobs are DISCOURAGED WORKERS and are no longer considered unemployed, rather, they have dropped out of the labor force. Discouraged workers are not accounted for in unemployment data.

2. Construct a weighted price index, using a set of data provided.

HOW TO: Refer to pages 303 – 305 in the textbook (Pearson Baccalaureate Economics)  for a worked solution to this type of problem. It’s not difficult math, you just have to know how to do it.

3. Calculate the inflation rate from a set of data.

HOW TO: The inflation rate = (CPI year 2 – CPI year 1)/CPI year 1. It is the rate of change in the CPI between two years. You do NOT always simply take the CPI and calculate the rate of change since it was 100. This would tell you how much inflation there was since the base year, but inflation is usually measured between two years.

4. Calculate the rate of economic growth from a set of data.

HOW TO: The rate of economic growth is the percentage change in the real GDP between two periods. = (GDP year 2 – GDP year 1)/GDP year 1

5. Calculate the marginal rate of tax and the average rate of tax from a set of data.

HOW TO: Refer to pages 361 – 362 in the text. The important thing here is to take your time and do the math very carefully.

The difference between the marginal rate and the average rates is as follows:

Assume the marginal tax rates for Country S are:


0-20,000 – 5%

20,001 – 50,000 – 15%

50,001 – 100,000 – 25%

100,001 – above – 35%

Assume an individual earns $75,000. Calculate:

    • The amount of tax he will pay:
    • He will pay 5% on the first 20,000. 20,000 x 0.05 = $1,000
    • He will pay 15% on the NEXT 30,000 (up to $50,000). 30,000 x 0.15 = $4,500
    • He will pay 25% on the NEXT $25,000 (the income he earns between $50,000 and $75,000). 25,000 x 0.25 = $6,250.
    • Total tax paid = 1,000+4,500+6,250 = $11,750
    • His average tax rate: This is his total tax liability divided by his income = $11,750 / $75,000 = 0.1567 x 100 = 15.67%.

You may also be given data on a INDIRECT taxes, which are taxes on consumption (such as a VAT). You may be told that the same individual consumes $45,000 of his income, of which 8% was paid in consumption taxes. Calculate the percentage of his income paid in indirect taxes:

$45,000 x 0.08 = $3,600 paid in indirect taxes.

$3,600 / $75,000 = 0.048 x 100 = 4.8% of his income paid in indirect taxes.

Section 3 International Economics

3.1 Free trade:
1. Calculate opportunity costs from a set of data in order to identify comparative advantage.

HOW TO: You may be given a production possibilities table OR a production possibilities curve for two countries. With either of these, you can calculate the opportunity costs of the countries for the two goods shown and determine comparative advantage.

For example: Assume Country S and Country I can produce the following amounts of wine and cheese on a single hectare of land

    • Country S: 4 barrels of wine and 5 tons of cheese
    • Country I: 8 barrels of wine and 8 tons of cheese

If the two countries were to specialize and trade, who should produce what?

    • In country S: 4w = 5c so 1w = 1.25c.
    • 5c = 4w, so 1c = 0.8w
    • In country I: 8w = 8c, so 1w=1c

In Country S, 1 ton of cheese costs only 0.8 ton of wine, while 1 barrel of wine costs 1.25 cheeses. In Country I cheese “costs” more (1 ton of wine), while wine “costs” less (only 1 ton of cheese).

So Country S should specialize in cheese, because it is cheaper, and Country I in wine. The two countries can then trade and enjoy the foreign produced good at a lower opportunity cost than they could have achieved domestically.

3.2 Protectionism:
1. Calculate from diagrams the effects of imposing a tariff on imported goods on different stakeholders, including domestic producers, foreign producers, consumers and the government.

HOW TO: If you are comfortable with the tariff diagram and can identify the different areas identified above, then you simply find the AREA of those shapes on the graph to determine the costs, benefits, and revenues necessary.

2. Calculate from diagrams the effects of setting a quota on foreign producers on different stakeholders, including domestic producers, foreign producers, consumers and the government.

HOW TO: Same as for tariffs. Once you are familiar with the graph, simply find the areas representing the impact on each of the stakeholders.

3. Calculate from diagrams the effects of giving a subsidy to domestic producers on different stakeholders, including domestic producers, foreign producers, consumers and the government.

HOW TO: Calculate the areas on a graph! EASY!

3.3. Exchange Rates:
1. Calculate the value of one currency in terms of another currency.

HOW TO: If you know the price of one currency in terms of another, you can quickly find the price of the other.

For example. If 1 euro = 1.2 CHF, then 1 CHF = 1/1.2 euro, or 0.83 Euro. The price of one currency is the inverse of the price of the other.

2. Calculate the exchange rate for linear demand and supply functions.

HOW TO: If you can calculate equilibrium price and quantity for a good using linear equations, then finding the equilibrium exchange rate is easy. Given the equations for two currencies, simply set them equal to each other and find the equilibrium.

Example: Assume the demand for Euros in Switzerland is represented by the equation Qd = 10 -2P, where P is the exchange rate of the Euro in CHF.

Supply of Euros in Switzerland is represented by the equation Qs = -3 + 4P where P is the exchange rate of the Euro in CHF.

3. Calculate the equilibrium exchange rate of the Euro in Switzerland.

Set the demand and supply equal to one another: 8 – 4P = -4 + 6P, and solve for P.

12 = 10P.
P = 12/10 = 1.2 CHF / Euro

4. Plot demand and supply curves for a currency from linear functions and identify the equilibrium exchange rate.

HOW TO: This is the same as plotting linear demand and supply equations for any good.

    • Find the q-intercept of demand (this is the ‘a’ variable)
    • Find the p-intercept of both demand and supply (set Q = 0 and solve for P in both equations)
    • Draw the demand curve by connecting the q-intercept and the p-intercept
    • Find the equilibrium price (or exchange rate in this case).
    • Plot the supply curve by connecting the p-intercept of supply and the equilibrium exchange rate.
    • Draw dotted lines over to the equilibrium exchange rate and down to the equilibrium quantity.

5. Using exchange rates, calculate the price of a good in different currencies.

HOW TO: If you know the price of a good in one currency and you know the exchange rate between that currency and another, you can always find the price of the good in the other currency.

For example: A hotel room in London costs 250 British Pounds per night. The British Pound exchange rate in Switzerland is 1.5 CHF / pound. How much does the London hotel room cost in CHF?

Convert the room’s price to CHF. So, 250 x 1.5 = 375 CHF per night.

6. Calculate the changes in the value of a currency from a set of data.

HOW TO: Consider the following. A London hotel room that costs 250 pounds per night used to cost 375 CHF. Following a change in the exchange rate, the same room now costs 400 CHF. Calculate the new exchange rate of British Pounds in Switzerland.

The old exchange rate was: 375 / 250 = 1.5 CHF / GBP. The new exchange rate, therefore, is 400 / 250 = 1.6 CHF / GBP

3.4 Balance of Payments:
1. Calculate elements of the balance of payments from a set of data.

HOW TO: You must know the components of a nation’s current and financial accounts, and be able to determine from a set of payments data which type falls into which category, and whether it counts as a credit or a debit.

For practice, complete the HL exercise on page 491 (with answers in the back of the book).

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