Development constraints interact and can reinforce one another.
Must know
- Low savings can constrain investment.
- Infrastructure skills and institutions affect productivity.
- Debt commodity dependence and external shocks create vulnerabilities.
Must know definitions
Terms of trade: the ratio of a country's export prices to its import prices; a fall (deterioration) means more exports are needed to pay for the same volume of imports.
Prebisch-Singer hypothesis: the theory that the terms of trade of countries exporting primary products decline over time relative to countries exporting manufactured goods.
Harrod-Domar model: in its simple form, growth equals the saving ratio divided by the capital-output ratio, assuming saving finances productive investment and ignoring depreciation.
Incremental capital-output ratio (ICOR): additional capital divided by the additional output it supports (ΔK/ΔY). A lower ratio indicates less additional capital per unit of extra output. The average capital-output ratio is K/Y; the simple fixed-coefficient growth model treats these ratios as equal and constant.
Savings gap: the shortfall between the savings actually generated in an economy and the savings needed to fund the investment required to achieve a target growth rate.
Foreign currency gap: the shortfall between a country's foreign currency earnings and its foreign currency needs (for imports, debt repayment, etc.).
Capital flight: the rapid outflow of financial assets or capital from a country, usually in response to instability or the search for higher returns abroad.
Dependency ratio: the ratio of the non-working-age population (children and elderly) to the working-age population.
Brain drain: the emigration of a country's skilled or educated workers to other countries.
Explain and apply
Mechanism in brief: Low saving can restrict investment, but extra finance yields little if unreliable power prevents production. Complementary constraints reduce expected returns and can reinforce a cycle of low productivity and income.
Distinguish: A correlation with low income does not by itself prove the cause; not every country faces the same binding constraint.
Use the extract: Identify the constraint preventing productive activity and show how it interacts with another constraint.
The impact of economic factors in different countries
Many developing and emerging economies face structural economic constraints that limit growth and development:
Volatility of commodity prices
Primary commodities tend to have price-inelastic demand and supply.
Small shifts in world demand or supply → large price swings.
Producer revenue and the country's foreign currency earnings fluctuate → uncertainty deters investment.
Primary product dependency (the Prebisch-Singer hypothesis)
A country is primary product dependent when the majority of its export earnings come from unprocessed commodities (e.g. minerals, oil, cash crops) rather than manufactured goods or services.
The Prebisch-Singer hypothesis argues that the terms of trade of primary product exporters decline relative to manufactured-good exporters over the long run.
One proposed mechanism is that demand for some primary products grows more slowly with world income than demand for manufactures → relative demand shifts towards manufactured goods. Income elasticities vary by product; this is not a universal classification.
Primary product prices are also more volatile because both demand and supply tend to be price-inelastic (see volatility of commodity prices above), so revenue is less predictable even before the long-run trend is considered.
Combined effect
if export prices rise more slowly than import prices → the terms of trade worsen → each unit exported buys fewer imports. Commodity booms, supply changes and product composition can reverse this movement.
The country must export a growing volume of primary products just to afford the same volume of manufactured imports → real income and living standards can stagnate even if export volumes are rising.
Persistent weak export purchasing power can restrict investment and living standards, especially with a narrow export base. Primary production does not inevitably cause low income; productivity, institutions and use of resource revenues matter.
Policy implication
diversification can reduce exposure to one commodity and develop higher-value activities, but requires skills, infrastructure and access to buyers. It has costs and is not guaranteed to succeed.
Savings gap (the Harrod-Domar model)
The model states
rate of economic growth = savings ratio ÷ capital-output ratio.
The incremental capital-output ratio measures extra capital per extra unit of output (ΔK/ΔY). The average ratio is K/Y. In the simple Harrod–Domar model, a constant ratio links investment to additional capacity; a lower assumed ratio gives more extra output for a given investment.
Higher domestic savings → more funds available for investment → faster capital accumulation → faster economic growth, for a given capital-output ratio.
Low household incomes leave little surplus after basic consumption → aggregate domestic saving may be insufficient to finance the investment needed for target growth. Use the saving-to-income ratio in this model; it is not automatically the marginal propensity to save.
This savings gap can, in principle, be filled from abroad via foreign aid, FDI or borrowing, but each carries its own costs (aid dependency, profit repatriation by foreign investors, or debt-servicing burdens), so closing the gap externally does not fully substitute for raising domestic savings.
Low growth from a persistent savings gap slows the rise in incomes and living standards, and can perpetuate a low-income, low-saving equilibrium (sometimes called a vicious circle of poverty).
Evaluation
The model links saving and capital accumulation under simplifying assumptions; it does not guarantee that finance reaches productive projects. Weak banks, poor project selection or shortages of skills can reduce investment returns. Technology and resource allocation can also change the capital needed per extra unit of output.
Foreign currency gap
Arises when a country's foreign currency earnings (mainly from exports) fall short of what it needs to pay for imports, debt repayments, and other foreign currency obligations.
Causes include low export earnings (e.g. from primary product dependency and weak terms of trade), rising import costs (e.g. a rise in the world oil price for a net oil importer), and large overseas debt repayments that must be made in a foreign currency (typically US dollars).
A foreign currency gap means the country cannot import enough capital goods, machinery, technology and intermediate inputs that are often not produced domestically and are essential for building productive capacity.
This directly slows economic growth, since much investment in developing economies depends on imported capital equipment, and can also lower living standards if the country cannot afford to import sufficient food, medicine or energy.
A persistent foreign currency gap can force a government to borrow more from abroad to bridge the shortfall, or to seek IMF support, which itself risks worsening the overseas debt problem.
Some economies try to close the gap by promoting export-led growth, encouraging inward FDI (which brings foreign currency directly), or diversifying away from a narrow, volatile export base.
Capital flight
Domestic savers move funds abroad in search of higher returns or greater security (e.g. in response to political instability or a weak banking system) rather than investing them at home.
Funds moved abroad can reduce domestic financing and increase demand for foreign currency → depreciation pressure and higher local-currency costs of foreign debt. The effect depends on replacement inflows, the exchange-rate regime and investor confidence.
Demographic factors (size and age distribution of population; migration)
High birth rates can create a large dependent child population relative to the working-age population. Population ageing can raise elderly dependency; both can put pressure on household resources and public services.
Some countries instead face ageing populations, partly a legacy of past policy (e.g. China's one-child policy), bringing different fiscal and labour-supply pressures.
Emigration of skilled workers ("brain drain") can also reduce a country's human capital base.
Debt (household and overseas)
High household debt is a problem if interest rates rise and borrowers cannot repay, risking damage to the banking system.
Foreign-currency debt becomes more costly in domestic currency after depreciation, unless foreign-currency earnings or hedging offset the exposure.
Debt-servicing costs can crowd out foreign currency needed for essential imports.
Access to credit and banking
Where financial systems are underdeveloped, individuals and small firms cannot easily borrow to start or expand businesses.
Without affordable credit, a viable firm cannot buy equipment or bridge the gap between paying suppliers and receiving sales revenue → investment and expansion are restricted. Credit alone achieves little if demand is weak or projects cannot repay the loan.
Infrastructure
Unreliable electricity interrupts production and requires costly backup generation; poor roads delay deliveries and damage goods → unit costs rise and market access narrows.
Lower expected returns deter domestic investment and FDI → productive capacity grows more slowly. Infrastructure improvements work best with maintenance, reliable institutions and the skills firms need to use them.
Education and skills
Limited education or training can restrict workers’ ability to operate equipment, adopt technology and move into more productive jobs → labour productivity and potential output grow more slowly.
The result depends on education quality and suitable employment: qualifications without relevant skills or job opportunities may not raise output. Health, infrastructure and institutions are complementary; low education spending does not mean the PPF cannot shift for other reasons.
The impact of non-economic factors in different countries
Growth and development can also be constrained by factors outside the purely economic sphere:
| Factor | How it constrains growth/development |
|---|---|
| Corruption | Diverts public funds away from productive spending (health, education, infrastructure); deters foreign investors worried about weak rule of law |
| Poor governance | Weak institutions, unclear property rights, and inconsistent policy undermine business confidence and long-term investment |
| Civil wars | Destroy physical and human capital, disrupt production and trade, and divert government spending toward conflict rather than development |
| Migration | Loss of working-age population and skilled workers ("brain drain") reduces the domestic labour force and human capital available for growth |
| Terrorism | Raises the cost of doing business (security, insurance), deters tourism and FDI, and can destroy infrastructure |
A common exam approach: for any data-response question on constraints, be ready to link a named economic factor to a named non-economic one — for example, poor governance often drives corruption, and both worsen a country's ability to attract the FDI it needs to close its savings or foreign currency gap.
Identify which obstacle must be eased first. Correlation with low income is not proof of causation; judge the proposed mechanism and whether complementary reforms are needed before expecting investment to raise growth.
Rapid recap
Finance: low saving or limited credit restricts viable investment; a foreign currency gap prevents essential imports. Debt service and capital flight can intensify these shortages.
Production: weak infrastructure raises costs; poor skills and health limit productivity. Finance achieves little if firms cannot use equipment effectively.
External exposure: volatile commodity receipts and a narrow export base make planning difficult. Terms-of-trade deterioration is a possible long-run problem, not an inevitable outcome.
Judge: identify the binding constraint and a complementary reform. Explain why easing that obstacle changes investment, productivity or access to essential services.
Diagram cue: trace the constraint → investment/productivity → growth.
Related chapters: Unit 4 chapter 1 (p. 4) · Unit 4 chapter 17 (p. 78)
Why this connects: Use the constraint diagnosis to choose a development strategy. Explain the obstacle removed and the complementary conditions needed for the strategy to work.