DP Economics SL 4.1 Benefits of International Trade

DP Economics SL 4.1 Benefits of International Trade - Full notes

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DP Economics SL | 4.1 Benefits of International Trade

DP ECONOMICS · UNIT 4: THE GLOBAL ECONOMY

4.1

Benefits of International Trade

Full notes for SL · IB-style

Contents

1	Why countries trade
2	The gains from trade
3	Absolute and comparative advantage
4	Sources of comparative advantage and its limitations
5	Free trade in a single market
6	The World Trade Organization
7	Why countries trade
8	Absolute advantage
9	Comparative advantage: calculations
10	Gains from specialization
11	Sources of comparative advantage
12	Limitations of comparative advantage
13	The World Trade Organization
14	Free trade: winners and losers
15	Trade and economies of scale
16	Trade and competition
17	Mixed review: worked problems
18	Additional exam-style practice
19	Trade and developing countries
20	Gains from trade on a PPC
21	Global value chains
22	Trade and sustainability
23	Common misconceptions and links
24	Exam-style question with markscheme
25	Check your understanding
26	Summary and topic map

These are full teaching notes. Read each section in order, try the Think about it question before you read on, and do every Quick check before moving to the next section.

Before you start

Rate yourself on each statement now, and again after you've worked through the notes. Shade R (not yet), A (getting there) or G (confident).

I can…	R	A	G
explain why countries trade and the benefits of international trade
distinguish absolute and comparative advantage
calculate opportunity costs and identify comparative advantage from data or PPCs
explain the sources and limitations of comparative advantage
show the effect of free trade on a domestic market
outline the role of the WTO

This booklet covers the SL syllabus for 4.1. The HL-only terms of trade are not included.

Guiding questions

Why does a country import goods it could make itself? Can a country that is worse at producing everything still gain from trade? Who wins and who loses when a country opens up to world markets?

How this topic is examined

Trade theory is the foundation of Unit 4. Paper 1 essays ask you to explain the gains from trade (often with comparative advantage) and to evaluate whether free trade benefits everyone. Paper 2 texts about trade agreements, exports or protection rely on the ideas here.

The comparative advantage calculation is examined often: work out opportunity costs both ways, identify which country should specialize in which good, and explain why both can gain.

Command term	What the examiner wants
Define	the precise meaning, ideally in the IB wording, in one or two sentences
Draw / Sketch	a fully labelled diagram with every axis, curve, equilibrium and change labelled
Explain	a causal chain linked to economic theory, usually supported by a diagram
Analyse	break a situation into its parts and trace the effects of each
Evaluate / Discuss	weigh up arguments, question assumptions and reach a justified conclusion using real-world examples
Calculate	calculate opportunity costs or index numbers step by step and state the conclusion

How to use these notes

Each section teaches one part of the syllabus in full. You'll see these boxes throughout; each has one job:

Box	What it's for
Think about it	a question to get you thinking before a section; the answer comes in the section
Key point	the one idea you must not forget
Common mistake	an error examiners see every year, and how to avoid it
In the real world	where the economics shows up outside the classroom
Try this	something quick you can do yourself to test the idea
Worked example	full solutions with IB-style marks (M1 method, A1 answer, R1 reasoning)
Quick check	short questions to test yourself at the end of each section

1 Why countries trade

Countries trade because they are different.

Think about it

Your phone contains parts from perhaps a dozen countries. Why isn't it made entirely in one country?

International trade is the exchange of goods and services across national borders. Countries export goods and services they produce to buyers abroad, and import goods and services from foreign producers.

Countries trade because they differ in their resources, skills, technology, climate and costs. Some goods cannot be produced at all in some countries (coffee in Iceland, oil in Japan), so they must be imported. Many others could be produced at home but are cheaper or better made abroad. By trading, countries can consume more and a wider range of goods than they could produce alone.

Trade has grown enormously since 1950, driven by falling transport costs (container shipping), better communications, trade liberalization through agreements and the WTO, and the rise of global supply chains, in which different stages of production happen in different countries.

Quick check

1. Define imports and exports.

2. Give two reasons why world trade has grown.

Answers: 1. imports: bought from abroad; exports: sold abroad 2. lower transport costs, liberalization, supply chains

2 The gains from trade

Trade raises output, lowers prices and widens choice.

Lower prices for consumers. Imports from lower-cost producers reduce prices, raising real incomes.

Greater choice. Consumers can buy goods not produced domestically and a wider variety of products.

Economies of scale. Firms selling to the world market can produce on a larger scale, lowering average costs. This is especially important for small countries whose domestic markets are too small for efficient production.

Increased competition. Foreign competition forces domestic firms to become more efficient and innovative, and limits domestic monopoly power.

Access to resources. Countries can obtain raw materials, energy and capital goods they lack, enabling production that would otherwise be impossible.

Efficient resource allocation. Countries specialize in what they produce most efficiently (Section 3), so world output rises.

Source of foreign exchange. Exports earn foreign currency to pay for imports.

Spread of technology and ideas, and closer political and cultural ties between countries.

Benefit	Who gains	Example
Lower prices	consumers	cheaper electronics imported from Asia
Greater choice	consumers	tropical fruit in cold countries
Economies of scale	firms	aircraft makers selling worldwide
Competition	consumers; economy	domestic car makers improving quality
Access to resources	firms	oil imports for energy
Foreign exchange	the economy	export earnings pay for imports

Quick check

1. Name four benefits of trade.

2. Why are economies of scale especially important for small countries?

Answers: 1. lower prices, choice, economies of scale, competition, resources, foreign exchange 2. domestic markets are too small for efficient production

3 Absolute and comparative advantage

Even a country that is worse at everything can gain from trade.

Think about it

A top surgeon is also a faster typist than her assistant. Should she type her own letters? Why not?

3.1 Absolute advantage

A country has an absolute advantage in producing a good if it can produce more of it than another country using the same quantity of resources. Adam Smith argued that if each country specializes in the good in which it has an absolute advantage and trades, both can gain.

3.2 Comparative advantage

David Ricardo showed something more surprising. Even if one country is better at producing everything, both countries can still gain from trade if they specialize according to comparative advantage.

A country has a comparative advantage in producing a good if it can produce it at a lower opportunity cost than another country. What matters is not who is better in absolute terms, but who gives up less of other goods to produce it. The surgeon is a better typist than her assistant, but every hour she spends typing costs her an hour of surgery, which is far more valuable. She has a comparative advantage in surgery; her assistant has a comparative advantage in typing.

Figure 1. PPCs for two countries using the same resources: A can produce 40 wheat or 20 cloth; B can produce 10 wheat or 30 cloth.

WORKED EXAMPLE 1 Identifying comparative advantage

Using the same resources, Country A can produce 40 tonnes of wheat or 20 metres of cloth; Country B can produce 10 tonnes of wheat or 30 metres of cloth. (a) Calculate the opportunity cost of each good in each country. (b) Identify comparative advantage. (c) Explain how both can gain.

Solution

(a) A: 1 wheat costs 20/40 = 0.5 cloth; 1 cloth costs 40/20 = 2 wheatM1 A1

B: 1 wheat costs 30/10 = 3 cloth; 1 cloth costs 10/30 = 0.33 wheatA1

(b) A has the lower opportunity cost of wheat, so A has a comparative advantage in wheat; B in clothA1

They trade at a rate between 0.5 and 3 cloth per tonne of wheat, e.g. 1 wheat for 1.5 cloth, so each gets the good more cheaply than producing itR1

Notice that opportunity costs for the two goods are reciprocals: if A gives up 0.5 cloth per wheat, it gives up 2 wheat per cloth. A country cannot have a comparative advantage in both goods. So every country has a comparative advantage in something, which is why trade can benefit all countries.

The terms of trade at which goods are exchanged (how much of one good trades for another) must lie between the two countries' opportunity costs; otherwise one country would be better off producing the good itself.

Common mistake

Assigning comparative advantage by who produces more. Comparative advantage depends on the lowest opportunity cost, not the highest output.

Quick check

1. Define comparative advantage.

2. Why can't a country have a comparative advantage in both goods?

3. Where must the terms of trade lie for both countries to gain?

Answers: 1. producing at a lower opportunity cost 2. opportunity costs are reciprocals 3. between the two countries' opportunity costs

4 Sources of comparative advantage and its limitations

Comparative advantage comes from differences; the theory rests on assumptions.

4.1 Sources of comparative advantage

Factor endowments. Countries differ in the quantity and quality of their land, labour and capital. Countries with abundant labour (Bangladesh) tend to have a comparative advantage in labour-intensive goods such as clothing; countries with abundant capital and skilled labour (Germany) in capital-intensive goods such as machinery; countries with fertile land or minerals in agriculture or mining.

Technology, skills and institutions also matter, and comparative advantage can change over time. South Korea moved from wigs and textiles in the 1960s to ships, cars and semiconductors by investing in education and capital.

4.2 Limitations of the theory

The theory of comparative advantage rests on simplifying assumptions, and its conclusions must be qualified.

Transport costs are ignored; they can wipe out the gains from trade for heavy or perishable goods.

Perfect factor mobility within countries is assumed: workers who lose jobs in import-competing industries are assumed to move easily to export industries. In reality they may become structurally unemployed.

Constant costs are assumed; in reality opportunity costs rise as countries specialize (concave PPCs), limiting specialization.

Full employment is assumed. Trade barriers and exchange rates are ignored.

Dependence and risk. Specializing in a few goods, especially primary commodities, exposes a country to price volatility and declining terms of trade.

Dynamic considerations. A developing country's current comparative advantage (raw materials) may not be the best basis for long-term development; infant industries may need protection to develop a new comparative advantage (4.3).

Quick check

1. Give two sources of comparative advantage.

2. Give three limitations of the theory.

Answers: 1. factor endowments, technology, skills 2. transport costs, immobile factors, rising costs, dependence

5 Free trade in a single market

Opening to trade lowers the domestic price to the world price.

Consider a country that is a small part of the world market for a good, so it can import as much as it wants at the world price (Pw) without affecting that price. The world supply curve is therefore horizontal at Pw.

Without trade, domestic equilibrium is where domestic demand meets domestic supply. If the world price is below the domestic equilibrium price, opening to free trade lowers the domestic price to Pw. Domestic consumers buy more (Q2), domestic producers supply less (Q1), and the gap, Q2 − Q1, is imported.

Figure 2. Free trade: the domestic price falls to the world price Pw; domestic production falls to Q1, consumption rises to Q2, and Q2 − Q1 is imported.

Consumers gain: they pay less and consume more, so consumer surplus rises. Domestic producers lose: they sell less at a lower price, so producer surplus falls and some workers may lose their jobs. Overall, the gain to consumers is larger than the loss to producers, so total welfare rises. This is the core argument for free trade, and also the reason why import-competing industries often lobby for protection (4.2 and 4.3).

Key point

Free trade raises total welfare, but the gains are spread across many consumers while the losses are concentrated on import-competing producers and their workers.

Quick check

1. What happens to domestic production when the world price is below the domestic price?

2. Who gains and who loses from free trade?

Answers: 1. it falls 2. consumers gain; import-competing producers lose

6 The World Trade Organization

Rules for world trade, agreed by its members.

The World Trade Organization (WTO), established in 1995 and succeeding the GATT (1947), has 164 members. Its main functions are to negotiate reductions in trade barriers through trade rounds, to set and enforce rules for international trade, and to settle trade disputes between members.

Key principles include non-discrimination (the most-favoured-nation principle: a trade advantage given to one member must be given to all) and national treatment (imported goods are treated the same as domestic goods once inside the country).

Critics argue that the WTO has favoured high-income countries, especially by allowing large agricultural subsidies in rich countries while pushing developing countries to open their markets; that negotiations have stalled (the Doha Round, launched in 2001, never concluded); and that its dispute settlement system has been weakened since 2019 because its appeals body has lacked members.

Quick check

1. Name the three main functions of the WTO.

2. What is the most-favoured-nation principle?

Answers: 1. negotiate lower barriers, set rules, settle disputes 2. an advantage given to one member must be given to all

7 Why countries trade

Gains from exchange.

Countries trade to obtain goods they cannot produce (resources, climate), to buy goods more cheaply, to access larger markets and economies of scale, to increase choice and competition, and to obtain technology and ideas.

WORKED EXAMPLE 2 Benefits (standard)

List four benefits of international trade.

Solution

Lower prices; greater choiceA1

Economies of scale; access to resources and technologyA1

8 Absolute advantage

Producing more with the same resources.

A country has an absolute advantage in a good if it can produce more of it than another country with the same resources. If each country has an absolute advantage in a different good, both gain from specialization and trade.

Country	Wheat (tonnes per worker)	Cloth (metres per worker)
A	10	4
B	6	8

WORKED EXAMPLE 3 Absolute advantage (standard)

Identify which country has an absolute advantage in each good.

Solution

A in wheat (10 > 6)A1

B in cloth (8 > 4)A1

9 Comparative advantage: calculations

Lower opportunity cost.

A country has a comparative advantage in a good if it can produce it at a lower opportunity cost than another country. Even if one country has an absolute advantage in both goods, both can gain by specializing according to comparative advantage.

Country	Rice (per worker)	Phones (per worker)
X	20	10
Y	6	6

WORKED EXAMPLE 4 Opportunity costs (exam level)

Calculate opportunity costs and identify comparative advantages.

Solution

X: 1 rice costs 0.5 phones; 1 phone costs 2 riceM1 A1

Y: 1 rice costs 1 phone; 1 phone costs 1 riceA1

X has comparative advantage in rice; Y in phonesR1

Quick check

1. Within what range of terms of trade (rice per phone) would both gain?

Answers: 1. between 1 and 2 rice per phone

10 Gains from specialization

Showing the gain.

When each country specializes in its comparative advantage good, total world output increases. Trade at terms between the two opportunity costs allows both to consume beyond their own PPCs.

WORKED EXAMPLE 5 Total output (exam level)

Each country has 10 workers. Before trade, each puts 5 workers on each good. After trade, Y specializes fully in phones and X puts 8 workers on rice and 2 on phones. Compare world output.

Solution

Before: rice 100 + 30 = 130; phones 50 + 30 = 80A1

After: rice 160; phones 20 + 60 = 80A1

Same phones, 30 more tonnes of rice: a gain from specializationR1

11 Sources of comparative advantage

Why costs differ.

Differences in factor endowments (land, labour, capital), technology, skills, climate and institutions give countries different opportunity costs. The Heckscher–Ohlin theory states that countries export goods that use their abundant factors intensively.

WORKED EXAMPLE 6 Factor endowments (standard)

Explain why Bangladesh has a comparative advantage in clothing.

Solution

Abundant, relatively low-cost labourR1

Clothing production is labour-intensiveR1

12 Limitations of comparative advantage

Real-world complications.

The theory assumes constant costs, no transport costs, perfect factor mobility within countries, full employment and free trade. In reality, transport costs, trade barriers, diminishing returns and adjustment costs (unemployment in declining industries) reduce gains.

Quick check

1. Give two limitations of the theory of comparative advantage.

Answers: 1. ignores transport costs; assumes factors move easily between industries

13 The World Trade Organization

Rules for trade.

The WTO sets rules for international trade, negotiates trade liberalization, and settles disputes between members. Its principles include non-discrimination (most-favoured nation) and reducing trade barriers. Critics argue it favours developed countries and its dispute system has been weakened.

In the real world

The WTO's Appellate Body has been unable to hear new appeals since December 2019 because the United States blocked the appointment of new judges.

Quick check

1. State two functions of the WTO.

Answers: 1. negotiate trade agreements; settle trade disputes

14 Free trade: winners and losers

Distribution of gains.

Consumers gain from lower prices; exporting firms and their workers gain; import-competing firms and their workers may lose. Overall gains usually exceed losses, but losers may need support (retraining, compensation).

WORKED EXAMPLE 7 Stakeholders (exam level)

Discuss the effects of free trade on different stakeholders.

Solution

Consumers: lower prices, more choiceR1

Import-competing industries: job losses; exporters gainR1

15 Trade and economies of scale

Bigger markets.

Access to world markets lets firms produce on a larger scale, lowering average costs. This is especially important for small countries with limited domestic markets.

Quick check

1. Why do small countries gain particularly from trade?

Answers: 1. access to larger markets allows economies of scale

16 Trade and competition

Efficiency effects.

Imports increase competition, pushing domestic firms to become more efficient and innovative, reducing monopoly power.

Quick check

1. How can trade reduce monopoly power?

Answers: 1. foreign competitors provide alternatives for consumers

17 Mixed review: worked problems

Bringing the ideas together.

WORKED EXAMPLE 8 Mixed problem (exam level)

Country P can produce 40 cars or 80 computers; country Q 30 cars or 30 computers (straight-line PPCs). Identify comparative advantages.

Solution

P: 1 car costs 2 computers; Q: 1 car costs 1 computerM1

Q has comparative advantage in cars; P in computersA1 A1

18 Additional exam-style practice

Paper 1 and Paper 3.

WORKED EXAMPLE 9 Paper 1 part (b) (exam level)

Evaluate the view that free trade benefits all countries. [15]

Solution

Comparative advantage with numerical or PPC illustrationR1 R1

Losers within countries; developing country concernsR1

Assumptions, adjustment costs; judgementR1 R1

19 Trade and developing countries

Opportunities and risks.

Trade can raise growth through exports, foreign exchange and technology transfer, but dependence on a few primary commodities exposes countries to volatile prices and declining terms of trade.

Quick check

1. Why can dependence on commodity exports be risky?

Answers: 1. volatile prices and possibly declining terms of trade

20 Gains from trade on a PPC

Consuming beyond the PPC.

After specialization and trade, a country can consume a combination outside its own PPC: the trade line shows possible consumption points at the terms of trade.

Figure 3. A PPC: trade allows consumption beyond the curve.

Quick check

1. What determines the slope of the trade line?

Answers: 1. the terms of trade

21 Global value chains

Trading in tasks.

Modern trade often involves global value chains: different stages of production occur in different countries (design in the US, components in Korea, assembly in China). Countries specialize in tasks rather than whole products.

Quick check

1. Give an example of a global value chain.

Answers: 1. smartphones: design, components and assembly in different countries

22 Trade and sustainability

Environmental costs.

Trade increases transport emissions and may shift polluting production to countries with weaker regulations ('pollution havens'). It can also spread green technology. Sustainable trade policies include carbon border adjustments.

Quick check

1. What is a carbon border adjustment?

Answers: 1. a charge on imports reflecting their carbon emissions

23 Common misconceptions and links

Students often think…	Actually…
comparative advantage goes to the country that produces more	it goes to the lower opportunity cost producer
a country better at everything cannot gain from trade	both gain by specializing in comparative advantage
free trade benefits everyone	total welfare rises, but import-competing producers and workers lose
the WTO sets world prices	it sets trade rules and settles disputes

How 4.1 connects to the rest of the course

Topic	Connection
1.1 PPC and opportunity cost	the basis of comparative advantage
4.2 and 4.3 Protection	arguments against free trade
4.4 Economic integration	trade agreements
4.9 Barriers to development	dependence on primary commodities

24 Exam-style question with markscheme

Try this under exam conditions (about 18 minutes) before reading the markscheme.

Figure 4. PPCs for two countries.

Text A. Two countries are negotiating a free trade agreement. Country A is better at producing both wheat and cloth, and some politicians in Country B argue that B cannot gain from trade with A.

(a) Define comparative advantage. [2]

(b) Calculate the opportunity cost of 1 tonne of wheat in each country (A: 40 wheat or 20 cloth; B: 10 wheat or 30 cloth). [2]

(d) Explain two limitations of the theory of comparative advantage. [4]

Markscheme

Part	Answer	Marks
(a)	producing a good at a lower opportunity cost	A1
	than another country	A1
(b)	A: 0.5 cloth	A1
	B: 3 cloth	A1
(c)	A specializes in wheat, B in cloth	R1
	total output rises	R1
	trade at terms between 0.5 and 3 cloth per wheat	R1
	both consume beyond their PPCs	R1
(d)	e.g. transport costs	R1 A1
	e.g. immobile factors / structural unemployment	R1 A1

Examiner's comments. In (c), the best answers used the opportunity costs from (b) to justify both the specialization and the trade ratio. Answers that stated Country A should produce both goods confused absolute and comparative advantage.

25 Check your understanding

Section A: multiple choice

1. A country has an absolute advantage when it

A. can produce more of a good with the same resources B. has a lower opportunity cost C. imports a good D. exports everything

2. Comparative advantage is based on

A. higher output B. lower wages only C. lower opportunity cost D. larger population

3. Free trade benefits consumers through

A. higher prices B. lower prices and more choice C. fewer goods D. less competition

4. A source of comparative advantage is

A. identical technologies B. equal wages everywhere C. tariffs D. differences in factor endowments

5. If A's opportunity cost of 1 wheat is 0.5 cloth and B's is 3 cloth, A should specialize in

A. cloth B. wheat C. both D. neither

6. World price below domestic equilibrium means a country will

A. import the good B. export the good C. not trade D. subsidise production

7. Which group may lose from free trade?

A. consumers B. exporters C. firms using imported inputs D. workers in import-competing industries

8. The WTO aims to

A. set exchange rates B. lend to poor countries C. reduce trade barriers and settle disputes D. control inflation

Section B: structured

9. Explain four benefits of international trade. [8]

10. Using a diagram, explain the effect of free trade on domestic consumers and producers. [4]

11. Explain why comparative advantage can change over time. [3]

Answers

1. A 2. C 3. B 4. D 5. B 6. A 7. D 8. C

9. Lower prices, choice, economies of scale, competition, resources, foreign exchange, with explanation.

10. Price falls to Pw; consumption rises, domestic output falls; imports Q2 − Q1; consumers gain, producers lose.

11. Investment in education and capital, new technology; e.g. South Korea moved from textiles to electronics.

26 Summary and topic map

Idea	Remember
Gains from trade	lower prices, choice, economies of scale, competition, resources
Absolute advantage	more output with the same resources
Comparative advantage	lower opportunity cost
Terms of exchange	between the two opportunity costs
Limitations	transport, immobility, rising costs, dependence
Free trade diagram	price falls to Pw; imports Q2 − Q1
WTO	negotiation, rules, disputes; MFN

Before the exam, make sure you…

•calculate opportunity costs both ways
•assign comparative advantage by lowest opportunity cost
•show winners and losers of free trade
•evaluate with the limitations of the theory

Benefits of International Trade on one page

Cover this page with a sheet of paper and try to rebuild it from memory. Whatever you can't recall is what to revise next.

Figure 5. Topic map for Benefits of International Trade.

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