The Global Economy

Videos on this page: Watch: Comparative Advantage and Trade · Watch: Exchange Rates and Balance of Payments

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International Trade

International trade allows countries to specialise in what they produce most efficiently, raising living standards globally. The IB syllabus examines the theory of comparative advantage, the gains from trade, and the effects of trade restrictions.

Why Countries Trade

Countries trade because they differ in their productive capabilities. Trade allows each country to specialise in what it produces most efficiently and to obtain goods it cannot produce as cheaply domestically.

Two theories of trade advantage:

Absolute Advantage

A country has an absolute advantage in producing a good if it can produce more of that good with the same resources than another country (or the same amount with fewer resources).

Example:

Country	Output per worker per day: Wheat	Output per worker per day: Cloth
Country A	10 units	5 units
Country B	4 units	8 units

Country A has an absolute advantage in wheat (10 > 4). Country B has an absolute advantage in cloth (8 > 5). Both can gain by specialising and trading.

Comparative Advantage

Comparative advantage is the ability to produce a good at a lower opportunity cost than another country. This is the more powerful and more frequently tested theory.

Key insight: Even if one country has an absolute advantage in producing everything, trade is still mutually beneficial — each country should specialise in the good for which it has the lower opportunity cost.

Calculating opportunity cost:

Using the table above:

• Country A: To produce 1 unit of cloth, it gives up $\frac{10}{5} = 2$ units of wheat. To produce 1 unit of wheat, it gives up $\frac{5}{10} = 0.5$ units of cloth.
• Country B: To produce 1 unit of cloth, it gives up $\frac{4}{8} = 0.5$ units of wheat. To produce 1 unit of wheat, it gives up $\frac{8}{4} = 2$ units of cloth.

Country A’s comparative advantage: Wheat (opportunity cost of 0.5 cloth, versus Country B’s 2 cloth).

Country B’s comparative advantage: Cloth (opportunity cost of 0.5 wheat, versus Country A’s 2 wheat).

Conclusion: Both countries benefit if Country A specialises in wheat and Country B in cloth, and they trade at a price between 0.5 and 2 units of cloth per unit of wheat.

Terms of Trade

The terms of trade (ToT) measure the relative price of a country’s exports compared to the price of its imports.

$\text{Terms of Trade} = \frac{\text{Index of export prices}}{\text{Index of import prices}} \times 100$

Interpretation:

• An improvement in the terms of trade (ToT rises): export prices rise relative to import prices — the country can buy more imports for a given volume of exports. Generally beneficial.
• A deterioration in the terms of trade (ToT falls): export prices fall relative to import prices — the country must export more to buy the same volume of imports. Detrimental, especially for commodity-exporting developing nations.

Causes of ToT changes:

• Changes in world commodity prices (e.g., oil price shocks, coffee price volatility).
• Exchange rate changes (currency appreciation → export prices rise in foreign currency → ToT may improve).
• Inflation differentials between countries.

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Free Trade vs Protectionism

Free trade allows goods and services to move across borders without government-imposed barriers, enabling specialisation according to comparative advantage.

Protectionism involves government policies that restrict imports to protect domestic industries.

The Case for Free Trade

• Efficiency gains: Resources are allocated according to comparative advantage — global output is maximised.
• Consumer benefits: Lower prices and greater variety through access to cheaper imports.
• Economies of scale: Firms can produce for larger global markets, reducing average costs.
• Competition: Exposure to foreign competition encourages domestic efficiency and innovation.
• Dynamic gains: Technology transfer, learning-by-doing spillovers.

Protectionist Instruments

Tariffs

A tariff is a tax imposed on imported goods.

Diagram analysis:

• World price $P_w$ is below the domestic equilibrium price.
• Without tariff: domestic quantity supplied $Q_1$, domestic quantity demanded $Q_4$, imports = $Q_4 - Q_1$.
• Tariff $t$ raises the price to $P_w + t$.
• At the higher price: domestic supply rises to $Q_2$, demand falls to $Q_3$, imports fall to $Q_3 - Q_2$.
• Effects on welfare:
  • Consumers lose surplus (area A + B + C + D) — they pay more and buy less.
  • Domestic producers gain surplus (area A).
  • Government gains tariff revenue (area C = tariff per unit × import quantity).
  • Net welfare loss = triangles B + D (production inefficiency + consumption inefficiency — the deadweight welfare loss).

Import Quotas

An import quota is a direct quantitative limit on the volume of a good that can be imported.

Diagram analysis: A quota shifts the domestic supply curve right by the quota amount. The price effect is similar to a tariff — domestic price rises above $P_w$.

Key difference from a tariff: The revenue equivalent of a tariff (area C in the tariff diagram) goes instead to foreign exporters (or domestic importers who receive import licences) — not to the domestic government. This makes quotas generally less efficient than tariffs from the domestic economy’s perspective.

Subsidies to Domestic Producers

A subsidy to domestic producers reduces their costs, enabling them to compete with cheaper imports without raising the consumer price.

Diagram analysis: Domestic supply shifts right. The world price is unchanged. Domestic quantity supplied increases; import volume decreases. Consumer price is unchanged (still at $P_w$).

Effect: Domestic consumers are not worse off (price is unchanged). Domestic producers are protected and expand output. The government bears the fiscal cost.

Administrative Barriers (Non-Tariff Barriers)

• Health and safety standards: Domestic standards that imports must meet — if set above international norms, they act as barriers.
• Bureaucratic customs procedures: Delays and paperwork impose costs on importers.
• Local content requirements: Rules requiring domestic inputs in production.
• Voluntary export restraints (VERs): Agreements where foreign firms “voluntarily” limit exports under threat of tariffs.

Arguments for Protectionism

• Infant industry argument: New domestic industries may need temporary protection to develop economies of scale before they can compete internationally. (Counter: protection may become permanent; difficult to pick winning industries.)
• National security: Strategic industries (defence, food, energy) should not depend on foreign suppliers.
• Protect employment: Prevent job losses in import-competing industries. (Counter: resources are more efficiently redeployed elsewhere; retaliation may destroy export jobs.)
• Anti-dumping: Respond to foreign firms selling below cost (dumping) to gain market share.
• Correct a trade deficit: Reduce imports to improve the current account. (Counter: trade deficits may reflect efficient capital inflows; protectionism invites retaliation.)

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Economic Integration

Economic integration describes the degree to which countries remove barriers to trade and coordinate economic policies among themselves.

Levels of Integration (from least to most integrated)

Level	Key feature	Example
Preferential Trade Agreement (PTA)	Reduced (not zero) tariffs among members	Various bilateral deals
Free Trade Area (FTA)	Zero tariffs among members; each keeps own external tariffs	NAFTA/USMCA, ASEAN
Customs Union	FTA + common external tariff	Mercosur
Common Market	Customs union + free movement of labour and capital	EU Single Market (pre-political union)
Economic Union	Common market + harmonised economic policies	European Union
Monetary Union	Economic union + single currency	Eurozone

Trade creation: Integration leads to lower-cost imports replacing higher-cost domestic production — efficiency gain.

Trade diversion: Lower-cost imports from outside the bloc are replaced by higher-cost imports from within the bloc (because intra-bloc tariffs are removed but external tariffs remain). This is a welfare loss.

The World Trade Organization (WTO)

The WTO is the multilateral institution that:

• Administers international trade rules (agreements governing tariffs, services, intellectual property).
• Provides a dispute settlement mechanism for trade conflicts.
• Promotes trade liberalisation through negotiating rounds (e.g., the Doha Development Round).

Principles: Non-discrimination (Most Favoured Nation clause — tariff concessions given to one member must be given to all); National Treatment (imported goods must be treated no less favourably than domestic goods once inside the border).

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Exchange Rates

An exchange rate is the price of one currency in terms of another.

Floating Exchange Rate

In a freely floating (flexible) exchange rate system, the exchange rate is determined entirely by the forces of supply and demand in the foreign exchange market. The government and central bank do not intervene.

Demand for a currency comes from:

• Foreign buyers of domestic exports (need domestic currency to pay).
• Foreign investors buying domestic assets.
• Speculation (anticipating appreciation).

Supply of a currency comes from:

• Domestic buyers of imports (supply domestic currency to buy foreign currency).
• Domestic investors buying foreign assets.
• Speculation (anticipating depreciation).

Determinants of exchange rate:

• Relative inflation rates (higher inflation → currency depreciates).
• Relative interest rates (higher rates attract capital inflows → currency appreciates).
• Current account balance (persistent deficits → currency depreciation tendency).
• Speculation and market sentiment.
• Economic growth prospects.

Fixed Exchange Rate

In a fixed (pegged) exchange rate system, the government or central bank sets the exchange rate at a specific value and intervenes to maintain it.

To defend an overvalued fixed rate: The central bank must buy domestic currency using its foreign exchange reserves (or raise interest rates to attract capital inflows).

To defend an undervalued fixed rate: The central bank sells domestic currency (buying foreign currency), accumulating reserves.

Problems with a fixed rate:

• Requires large foreign exchange reserves to defend.
• A speculative attack can exhaust reserves, forcing a devaluation (e.g., 1992 UK ERM crisis).
• Loses monetary policy independence — interest rates must serve the exchange rate target, not domestic macro goals.

Managed Float (Dirty Float)

A managed float is a hybrid system in which the exchange rate is primarily market-determined, but the central bank intervenes occasionally to reduce excessive volatility or to keep the rate within an informal target range.

Most major economies operate managed floats in practice.

Effects of Exchange Rate Changes

Currency depreciation (domestic currency falls in value):

• Exports: Domestic goods become cheaper in foreign currency → export volume may rise.
• Imports: Foreign goods become more expensive in domestic currency → import volume may fall.
• Current account: If the Marshall-Lerner condition holds, depreciation improves the current account balance.
• Inflation: Import prices rise → cost-push inflation (imported inflation).
• Debt: Foreign-currency-denominated debt increases in domestic currency terms.

Currency appreciation (domestic currency rises in value):

• Exports become more expensive → export volume may fall.
• Imports become cheaper → import volume may rise.
• Current account may deteriorate.
• Inflation reduced (cheaper imports).

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Balance of Payments

The balance of payments (BoP) is a systematic record of all economic transactions between residents of a country and the rest of the world over a given period.

Structure of the Balance of Payments

Current Account:

• Trade in goods (visible trade): Exports minus imports of physical goods.
• Trade in services (invisible trade): Tourism, financial services, education, transport.
• Primary income: Investment income (dividends, interest) and compensation of employees (cross-border workers).
• Secondary income: Transfers — foreign aid, remittances, contributions to international organisations.

Capital Account: Mainly capital transfers and acquisition/disposal of non-produced, non-financial assets (e.g., debt forgiveness, patents). Relatively small in most economies.

Financial Account: Net purchases and sales of financial assets:

• Direct investment (FDI).
• Portfolio investment (stocks, bonds).
• Other investment (bank loans, trade credit).
• Reserve assets (changes in the central bank’s foreign exchange reserves).

Current Account Balance

$\text{Current account balance} = X - M + \text{Primary income net} + \text{Secondary income net}$

Current account deficit: Imports of goods, services, and income exceed exports — the country is spending more abroad than it is earning from abroad.

Current account surplus: The country earns more from abroad than it spends — a net creditor position.

Relationship Between the Accounts

The BoP always balances by accounting convention:

$\text{Current Account} + \text{Capital Account} + \text{Financial Account} = 0$

A current account deficit must be financed by a surplus on the financial account — foreign investors must be buying domestic assets (FDI, bonds, shares) to provide the foreign currency that pays for the import excess. Alternatively, the central bank depletes its reserves.

Sustainability: A persistent current account deficit is sustainable only if foreign investors continue to finance it. If confidence falls, the financing can dry up rapidly — forcing a painful adjustment (sharp currency depreciation, rise in domestic interest rates).

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Economic Development

Economic development goes beyond GDP growth to encompass improvements in living standards, health, education, and equality. Developing economies face distinct structural challenges that require tailored policy responses.

Characteristics of Developing Countries

Economic development is a multi-dimensional concept that includes not just income growth but also improvements in living standards, health, education, freedom, and sustainability.

Common characteristics of lower-income developing countries:

• Low GDP per capita: Insufficient income to meet basic needs.
• High proportion of primary sector employment: Agriculture and resource extraction dominate; vulnerable to commodity price volatility.
• Poverty and inequality: High poverty rates, large informal sector, often high Gini coefficient.
• Poor infrastructure: Inadequate roads, power, water, sanitation — raises costs and reduces productivity.
• Low human development: High infant mortality, low life expectancy, limited access to education.
• Political instability and weak institutions: Corruption, poor rule of law, insecure property rights — deter investment.
• Dependence on foreign aid or remittances: Vulnerability to external shocks.

Barriers to Economic Development

Poverty trap: Low income → low savings → low investment → low growth → low income. Breaking out requires an external injection of capital (aid, FDI, remittances) or a structural transformation.

Lack of human capital: Poor nutrition and health reduce worker productivity. Limited education constrains technological adoption.

Lack of physical capital: Inadequate infrastructure and machinery.

Corruption and governance failures: Divert public resources from productive investment; deter private and foreign investment.

International trade barriers: Developed-country agricultural subsidies and tariffs restrict market access for developing-country exports, undermining comparative advantage.

Debt burden: Many developing countries carry heavy external debt — interest payments crowd out public spending on health, education, and infrastructure.

Brain drain: Skilled workers emigrate to higher-income countries — loss of human capital investment.

Strategies for Development

Strategy	Mechanism	Risk
Foreign aid	Transfers resources to fund investment	Dependency; corruption; fungibility
FDI attraction	Inflow of capital, technology, jobs	Profit repatriation; enclave industries
Microfinance	Small loans to entrepreneurs without collateral	High interest rates; overindebtedness
Fair trade	Higher prices for commodities from developing countries	Limited scale; may distort markets
Debt relief	Reduces debt service burden; frees fiscal space	Moral hazard for future lending
Trade liberalisation	Access to export markets encourages specialisation	Infant industries vulnerable; structural adjustment costs
Education and health investment	Build human capital — long-run productivity	Long time lags; requires sustained funding

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Sustainable Development

Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs (Brundtland Commission, 1987).

Three Dimensions of Sustainable Development

Economic sustainability: Growth must be based on productive investment and diversification, not depletion of non-renewable resources. GDP growth must be accompanied by improvements in productivity, not just resource extraction.

Social sustainability: Growth must be inclusive — reducing extreme poverty, improving access to healthcare and education, reducing gender and income inequality. Growth that benefits only a small elite is not socially sustainable (and may be politically unstable).

Environmental sustainability: Economic activity must be kept within planetary boundaries — respecting ecosystems, biodiversity, and climate stability. Non-renewable resources should be used at rates that allow substitution; renewable resources should not be harvested beyond their regeneration rate.

The UN Sustainable Development Goals (SDGs)

The 17 SDGs (adopted 2015, target year 2030) provide a global framework:

• SDG 1: No poverty
• SDG 7: Affordable and clean energy
• SDG 10: Reduced inequalities
• SDG 13: Climate action
• SDG 17: Partnerships for the goals

IB examiners expect students to apply SDG concepts when evaluating development strategies.

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HL Terms of Trade Calculations

The terms of trade index is calculated as:

$ToT = \frac{P_X}{P_M} \times 100$

where $P_X$ is the index of export prices and $P_M$ is the index of import prices, both relative to a base year (base = 100).

Change in terms of trade:

$\% \Delta ToT = \frac{ToT_{\text{new}} - ToT_{\text{old}}}{ToT_{\text{old}}} \times 100$

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HL Marshall-Lerner Condition and the J-Curve

HL examines the precise conditions under which a currency depreciation will improve a country’s current account balance, and why the response may follow a J-curve pattern in the short run before the long-run improvement materialises.

The Marshall-Lerner Condition

When a currency depreciates, the effect on the current account depends on the price elasticities of demand for exports and imports.

The Marshall-Lerner condition states that a currency depreciation will improve the current account balance if and only if the sum of the absolute values of the price elasticities of demand for exports and imports is greater than one:

$|PED_X| + |PED_M| > 1$

Intuition:

• A depreciation lowers the foreign-currency price of exports → demand for exports rises (if elastic, volume rise outweighs price fall → export revenue in domestic currency rises).
• A depreciation raises the domestic-currency price of imports → demand for imports falls (if elastic, import spending in domestic currency falls).
• If both elasticities are large enough, the combined volume effects dominate the price effects, and the current account improves.

If the condition is not met ($|PED_X| + |PED_M| < 1$): Demand for both exports and imports is inelastic — the volume responses are small relative to the price changes. Export revenue falls in foreign currency terms (price fell more than volume rose); import spending rises in domestic currency (price rose more than volume fell). The current account deteriorates.

The J-Curve Effect

The J-curve illustrates the typical pattern of the current account following a currency depreciation:

1. Short run (condition not met): Import and export contracts are pre-existing — volumes do not immediately change, but the price effects are felt immediately. Import costs rise in domestic currency (depreciation makes imports costlier), while export revenues in domestic currency do not rise quickly (foreign buyers have existing contracts). The current account deteriorates initially.

2. Medium to long run (condition met): Firms and consumers adjust behaviour. Exporters gain market share as foreign buyers switch to now-cheaper domestic goods. Domestic consumers substitute away from more expensive imports. Volumes adjust. If $|PED_X| + |PED_M| > 1$, the current account improves beyond its original level.

The J-curve shape: Starting at the pre-depreciation current account balance, the balance first worsens (the bottom of the J), then improves, eventually settling at a better position than before (the right arm of the J).

Current
account
balance
    |
    |                             /
    |                           /
    |_________________________/
  0 |       pre-depr. level
    |    \
    |     \
    |      \   (short-run deterioration)
    |       \____/
    |_______________________________________  Time
         Depreciation
              occurs here

Watch: Comparative Advantage and Trade

ACDCEcon (Jacob Clifford) · 8 min · Explains absolute and comparative advantage, opportunity cost calculations, and how to determine which country should specialise and trade — the exact skills tested in IB Paper 2 data-response questions on international trade.

Watch: Exchange Rates and Balance of Payments

EconplusDal · 12 min · Covers floating and fixed exchange rates, determinants of exchange rate changes, the balance of payments structure, and the Marshall-Lerner condition with J-curve diagrams — full HL Unit 4 coverage.

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Practice Questions

Short-answer (Paper 2 style):

1. The table below shows production data for two countries.

   Country	Rice (tonnes/worker/day)	Steel (tonnes/worker/day)
   X	12	3
   Y	8	4

   (a) Identify which country has an absolute advantage in each good. (2 marks) (b) Calculate the opportunity cost of producing one tonne of steel in each country and identify which country has a comparative advantage in steel. (2 marks)

2. Using a diagram, explain the effects of a tariff on consumers, domestic producers, and the government. (4 marks)

3. Distinguish between a current account deficit and a financial account surplus and explain how they are related. (4 marks)

4. Explain two barriers to economic development faced by lower-income countries. (4 marks)

5. HL A country has an export price index of 120 and an import price index of 96 (base year = 100 for both). Calculate the terms of trade and state whether this represents an improvement or deterioration from the base year. (4 marks)

6. HL Explain the Marshall-Lerner condition and explain why a depreciation may initially worsen the current account balance. (4 marks)

Essay questions (Paper 1 style):

7. (a) Explain, using the theory of comparative advantage, why countries benefit from free international trade. (10 marks) (b) Evaluate the case for protectionism in developing countries wishing to industrialise. (15 marks)

8. (a) Explain how a depreciation of the exchange rate affects a country’s macroeconomic performance. (10 marks) (b) Evaluate the effectiveness of exchange rate depreciation as a policy tool for correcting a current account deficit. (15 marks)

Answer guidance — Question 1

(a) Absolute advantage:

• Country X produces more rice per worker (12 > 8) → X has absolute advantage in rice.
• Country Y produces more steel per worker (4 > 3) → Y has absolute advantage in steel.

(b) Opportunity cost of 1 tonne of steel:

• Country X: To produce 1 tonne of steel, X gives up $\frac{12}{3} = 4$ tonnes of rice.
• Country Y: To produce 1 tonne of steel, Y gives up $\frac{8}{4} = 2$ tonnes of rice.

Country Y has the lower opportunity cost of producing steel (2 tonnes of rice vs. 4 tonnes of rice) → Country Y has a comparative advantage in steel.

(Therefore Country X has a comparative advantage in rice — opportunity cost 3/12 = 0.25 tonnes of steel per tonne of rice, versus Y’s 4/8 = 0.5 tonnes of steel per tonne of rice.)

Answer guidance — Question 5 (HL)

$ToT = \frac{P_X}{P_M} \times 100 = \frac{120}{96} \times 100 = 125$

The terms of trade index is 125, compared with the base year value of 100. This represents a 25% improvement in the terms of trade — the country can now obtain 25% more imports for a given volume of exports.

Possible causes: Export prices rising (e.g., a commodity boom), import prices falling (e.g., fall in the price of manufactured goods), or exchange rate appreciation.

Answer guidance — Question 8(b) evaluation points

A strong evaluation of exchange rate depreciation for correcting a current account deficit should include:

1. Marshall-Lerner condition (for — if met): If $|PED_X| + |PED_M| > 1$, depreciation will improve the current account in the medium to long run. Export volumes rise as domestic goods become cheaper abroad; import volumes fall as foreign goods become more expensive domestically.

2. J-curve effect (against — short run): In the short run, contracts are pre-set and behaviour is slow to change — the condition may not hold. The current account may deteriorate initially before improving. Policymakers must sustain the depreciation and tolerate the short-run worsening.

3. Inflation risk (against): Depreciation raises import prices, generating cost-push inflation and potentially demand-pull inflation (if export demand rises sharply). If domestic inflation exceeds the depreciation rate, real competitiveness gains are eroded.

4. Structural issues (against): If the current account deficit reflects structural lack of competitiveness (low productivity, poor quality), depreciation only provides temporary relief. Without supply-side improvements, competitiveness will erode again as domestic inflation catches up.

5. Debt implications (against): If the country holds significant foreign-currency-denominated debt, depreciation increases the debt burden in domestic currency terms — potentially causing financial instability.

6. Retaliation risk: Competitive depreciation (deliberately devaluing to gain trade advantage) can trigger retaliatory currency interventions or protectionist measures — a “currency war” that benefits no one.

Conclusion: Exchange rate depreciation can be an effective short-to-medium-run tool for improving the current account when the Marshall-Lerner condition holds and inflation is contained, but it is not a substitute for structural reforms that address the underlying productivity and competitiveness weaknesses driving the deficit. Its effectiveness depends critically on the elasticities of export and import demand, and on the inflationary environment.