IB Economics HL - Exam-Focused Revision Notes

Methodological Overview and Scope

These revision notes are structured around the textbook Economics for the IB Diploma by Ellie Tragakes (3rd edition, Cambridge University Press, 2020) and are fully aligned with the syllabus structure for first assessment in 2022. Priority tiers are established using public 2022–2026 Higher Level (HL) past-paper classification data to highlight high-frequency, core examination areas while retaining complete syllabus coverage.

Priority classifications are categorized as follows:

HIGH: Repeatedly examined, central concept, or heavily diagrammatic/policy-focused.
MEDIUM: Recurring concept worth thorough revision.
BASIC: Standard syllabus knowledge, presented concisely.

Revision Rule: Master the bold definition first, followed by the underlying economic mechanism, diagrammatic representation, mathematical formula, and evaluation points.

Per exam scope instructions, Unit 1 is omitted, and Market Power (perfect competition, monopoly, monopolistic competition, oligopoly, and abuse of market power) is excluded. The revision sequence follows Global Economics, Macroeconomics, and Microeconomics.

Recent HL examination patterns indicate the following key trends:

Global Economics: Floating exchange rates, balance-of-payments components, trade protection, and trade creation/diversion appear with high frequency.
Macroeconomics: Measurement of economic activity (specifically real versus nominal comparisons), AD-AS models, macroeconomic objectives, and policy interactions are consistently examined.
Microeconomics: Negative externalities represent one of the most frequently tested areas. Price elasticity of demand (PED) and subsidies recur regularly, while basic demand and supply concepts serve as essential foundations.

Part I: Global Economics

4.1 Benefits of International Trade

International trade [MEDIUM] is defined as the exchange of goods and services across national borders. Free trade [HIGH] refers to international trade that takes place without government-imposed barriers such as tariffs, quotas, or administrative restrictions. World price [MEDIUM] is the price at which a good is traded on the international market. Autarky [BASIC] describes a situation in which a country does not participate in international trade and is entirely self-sufficient.

To determine whether a nation will import or export a product upon opening to trade, compare the world price to the domestic equilibrium price:

If world price < domestic equilibrium price, the country imports the good.

$\text{Imports} = Q_d - Q_s \quad \text{at the world price}$

If world price > domestic equilibrium price, the country exports the good.

$\text{Exports} = Q_s - Q_d \quad \text{at the world price}$

Specialisation [HIGH] is the concentration of productive resources on a narrower range of goods and services in which a producer or country is relatively efficient. Absolute advantage [MEDIUM] is the ability of a country to produce a good using fewer resources than another country, or to produce more of a good with the same amount of resources. Comparative advantage [HIGH] is the ability of a country to produce a good at a lower opportunity cost than another country.

The opportunity cost calculations for two goods, $X$ and $Y$ , are given by:

$\text{Opportunity cost of } 1\,X = \frac{\text{maximum } Y}{\text{maximum } X}$

$\text{Opportunity cost of } 1\,Y = \frac{\text{maximum } X}{\text{maximum } Y}$

Comparative Advantage Exam Logic:

Calculate the opportunity cost of producing each good in each country.
The country with the lower opportunity cost possesses the comparative advantage in that good.
Each country specializes in producing the good in which it holds a comparative advantage.
Mutually beneficial terms of trade must lie between the two countries' opportunity costs.
Specialisation increases total combined global output, enabling countries to consume beyond their domestic Production Possibilities Curve (PPC).

Gains from trade [HIGH] refer to the increase in consumption possibilities and economic welfare resulting from specialisation and international exchange. Economies of scale [MEDIUM] are reductions in average production costs resulting from an increase in the scale of operation.

Main benefits of international trade include specialisation based on comparative advantage, increased efficiency, improved resource allocation, lower consumer prices, expanded consumer choice, access to larger foreign markets and economies of scale, increased competition, access to raw materials and foreign technology, and economic growth.

Limitations of comparative advantage include transport costs, structural unemployment during economic adjustment, negative externalities of production/transportation, imperfect factor mobility, dynamic changes in comparative advantage over time, risks of over-specialisation and economic dependence, and unequal distribution of trade gains.

Diagrams to know for this section:

Free-trade import diagram: Domestic supply ( $S$ ) and demand ( $D$ ) curves with a horizontal world price line ( $P_w$ ) below domestic equilibrium; clearly label $Q_s$ , $Q_d$ , and the quantity of imports.
Free-trade export diagram: Domestic $S$ and $D$ curves with a horizontal world price line ( $P_w$ ) above domestic equilibrium; clearly label $Q_d$ , $Q_s$ , and the quantity of exports.
Comparative advantage PPC / data-table diagram showing linear PPCs and opportunity-cost trade-offs.

4.2 Types of Trade Protection

Trade protection / protectionism [HIGH] is government intervention in international trade through barriers designed to restrict imports and protect domestic producers from foreign competition.

A tariff [HIGH] is a tax imposed on imported goods.

$\text{Tariff revenue} = \text{tariff per unit} \times \text{quantity of imports after tariff}$

Tariff Effects:

Domestic price rises from $P_w$ to $P_w + \text{tariff}$ .
Domestic production increases, domestic consumption falls, and import volume decreases.
Domestic producers gain (increased producer surplus); domestic consumers lose (decreased consumer surplus); government collects tariff revenue; foreign exporters lose market share and sales revenue.
Deadweight welfare loss occurs in two distinct areas: production inefficiency (allocating resources to higher-cost domestic producers) and consumption inefficiency (loss of consumer surplus due to lower consumption).

An import quota [HIGH] is a legal limit on the quantity or value of a good that may be imported into a country during a specified period. Quota rent [HIGH] is the extra revenue generated because the domestic price exceeds the world price on the restricted volume of imports.

Tariff vs. Quota Comparison:

Both measures raise the domestic price, increase domestic output, reduce domestic consumption, and lower import quantities. Under a tariff, the government receives tax revenue. Under a quota, quota rents accrue to licence holders, the government (if import licences are auctioned), or foreign exporters. A quota directly fixes the quantity of imports, whereas a tariff influences price, allowing supply and demand to determine the resulting import volume.

A production subsidy [HIGH] is a payment by the government to domestic producers that lowers their production costs and encourages domestic output.

$\text{Government subsidy expenditure} = \text{subsidy per unit} \times \text{domestic output after subsidy}$

Production Subsidy Effects:

Domestic production increases and imports fall.
Domestic consumers continue to pay the world price $P_w$ , so domestic consumption remains unchanged.
Domestic producers gain; government and taxpayers bear the financial burden; foreign exporters lose sales volume.
Creates less consumption distortion than a tariff or quota, but still promotes inefficient domestic production.

An export subsidy [MEDIUM] is a government payment to domestic producers for every unit of a good exported. Administrative barriers [MEDIUM] are regulatory rules, standards, or procedural requirements that make importing goods more difficult, expensive, or time-consuming.

Diagrams to know for this section:

Tariff diagram showing world price ( $P_w$ ), tariff-inclusive price ( $P_w + t$ ), import quantities before and after tariff, government revenue, and deadweight welfare loss triangles.
Quota diagram showing quota-constrained market supply, resulting domestic price increase, and quota rent rectangle.
Production subsidy diagram illustrating a downward shift in domestic supply, unchanged consumer price, higher price received by producers, and reduced import volume.
Export subsidy diagram illustrating domestic price adjustments, consumer losses, producer gains, and taxpayer costs.

4.3 Arguments For and Against Trade Protection

An infant industry [HIGH] is a newly established domestic industry that has not yet developed the scale or experience needed to compete effectively against established foreign producers. Dumping [MEDIUM] is the selling of exports in a foreign market at an unfairly low price, often below production cost or below the price charged in the home market. A trade war [MEDIUM] is a economic conflict in which countries retaliate against one another by imposing or raising trade barriers.

Arguments FOR Protection:

Protection of infant industries until they achieve economies of scale.
Protection of domestic employment in import-competing sectors.
National security considerations for strategic industries.
Maintenance of health, safety, and environmental standards.
Prevention of dumping and unfair foreign competition.
Diversification of the domestic industrial base.
Generation of government revenue (especially in developing economies).

Arguments AGAINST Protection:

Higher prices for domestic consumers.
Reduced availability and choice of goods.
Inefficiency among protected domestic firms due to lack of competition.
Misallocation of global and domestic resources.
Deadweight welfare losses.
Risk of trade retaliation by commercial partners.
Reduced export competitiveness due to higher input costs.
Susceptibility to political lobbying and permanent protection dependence.

Key Evaluation Sentences:

Infant-industry protection is stronger when it is temporary and tied to measurable efficiency gains; otherwise, firms may become dependent on protection.
Protecting employment in import-competing industries can cost jobs in export industries if trading partners retaliate.
A tariff may raise government revenue, but consumer surplus falls and resources may move away from comparative advantage.
The strength of the case depends on duration, size of the industry, likely retaliation, and whether market failure actually exists.

4.4 Economic Integration

Economic integration [HIGH] is the process by which countries reduce or remove trade and economic barriers between themselves and coordinate economic policies. A trading bloc [HIGH] is a group of countries that agree to reduce or eliminate trade barriers among member nations.

A preferential trade agreement (PTA) [BASIC] is an agreement offering participating nations preferential access to specific products by lowering trade barriers. A free trade area (FTA) [HIGH] is a group of countries that eliminate trade barriers among members while each member maintains its independent trade policy toward non-members. A customs union [HIGH] is a free trade area whose member states adopt a common external tariff policy toward non-member nations. A common market [HIGH] is a customs union that allows the free movement of factors of production—primarily labor and capital—between member states. A monetary union [MEDIUM] is an advanced stage of integration in which member countries share a common currency and a single monetary policy managed by a shared central bank.

$\text{PTA} \rightarrow \text{FTA} \rightarrow \text{Customs Union} \rightarrow \text{Common Market} \rightarrow \text{Monetary Union}$

As economic integration deepens, national economic policy independence decreases.

Trade creation [HIGH] is the replacement of higher-cost domestic production or higher-cost imports by lower-cost imports from a member country following economic integration. Trade diversion [HIGH] is the replacement of lower-cost imports from a non-member country by higher-cost imports from a member country because the non-member faces external trade barriers.

Memory Line:

Trade creation: High cost $\rightarrow$ Lower cost $\rightarrow$ Efficiency and welfare tend to rise.
Trade diversion: Low cost $\rightarrow$ Higher cost $\rightarrow$ Efficiency and welfare can fall.

Sovereignty [MEDIUM] is the independent authority of a national government to make its own economic and political decisions.

Benefits of Trading Blocs:

Expanded internal market size and trade volumes.
Increased competition and lower prices for consumers.
Access to regional economies of scale.
Greater foreign direct investment inflows.
Improved factor mobility within common markets.

Costs and Risks of Trading Blocs:

Potential for net trade diversion.
Unequal distribution of gains among member nations.
Structural unemployment during economic adjustment.
Reduced national policy independence and loss of sovereignty.
Complex policy coordination and potential inter-bloc trade conflicts.

4.5 Exchange Rates

An exchange rate [HIGH] is the price of one currency expressed in terms of another currency. The foreign exchange market [HIGH] is the global market in which national currencies are traded. A floating exchange rate [HIGH] is an exchange rate determined entirely by market demand and supply for the currency, without official central bank targets.

Appreciation [HIGH] is an increase in the value of a currency within a floating exchange-rate system. Depreciation [HIGH] is a decrease in the value of a currency within a floating exchange-rate system.

Demand for a Currency:

Foreigners demand a domestic currency to purchase exports, invest in domestic physical or financial assets, travel within the country, or hold currency reserves. Demand shifts rightward with rising export demand, increased inward foreign investment, higher relative domestic interest rates, bullish speculation, or enhanced international economic confidence.

Supply of a Currency:

Domestic residents supply their currency to obtain foreign exchange for purchasing imports, investing abroad, or traveling overseas. Supply shifts rightward with increasing import demand, rising outward foreign investment, lower relative domestic interest rates, or expectations of currency depreciation.

Currency Appreciation Effects:

Exports become more expensive to foreign buyers; imports become cheaper for domestic buyers.
Net exports ( $X - M$ ) and aggregate demand ( $AD$ ) tend to decrease.
Import costs decrease, reducing imported inflationary pressures.
Export-oriented industries experience reduced competitiveness, while domestic consumers and import-dependent firms benefit.

Currency Depreciation Effects:

Exports become cheaper to foreign buyers; imports become more expensive for domestic buyers.
Net exports ( $X - M$ ) and aggregate demand ( $AD$ ) tend to increase.
Import costs increase, raising imported inflationary pressures.
Exporting industries gain price competitiveness, while domestic consumers face higher prices for foreign goods.

A fixed exchange rate [HIGH] is an exchange rate set at an official value against another currency or basket of currencies and maintained through central bank intervention. Devaluation [HIGH] is an official decrease in the pegged value of a currency under a fixed exchange-rate regime. Revaluation [HIGH] is an official increase in the pegged value of a currency under a fixed exchange-rate regime.

A managed exchange rate / managed float [HIGH] is a regime in which the exchange rate is primarily market-determined, but the central bank periodically intervenes to prevent excessive volatility or steer the rate toward a target band. Foreign currency reserves [MEDIUM] are foreign assets and currencies held by a central bank to back liabilities and intervene in foreign exchange markets.

Central Bank Actions under Fixed/Managed Regimes:

To support a currency under downward pressure: The central bank purchases its own currency in foreign exchange markets using foreign reserves, or raises domestic interest rates to attract financial capital.
To manage a currency under upward pressure: The central bank sells its own currency and accumulates foreign exchange reserves, or lowers domestic interest rates.

Diagrams to know for this section:

Floating rate diagram: Currency demand and supply curves showing equilibrium price, rightward/leftward shifts, and resulting appreciation or depreciation.
Fixed rate diagram: Market supply and demand curves with an official pegged price set above or below equilibrium, illustrating resulting surpluses or shortages and central bank reserve intervention.
Managed float diagram: Market exchange rate model illustrating intervention boundaries and supply/demand shifts driven by official purchases or interest rate adjustments.

4.6 Balance of Payments

The balance of payments (BOP) [HIGH] is a comprehensive accounting record of all economic transactions between the residents of a country and the rest of the world over a specified period.

The current account [HIGH] records flows of trade in goods and services, primary income, and secondary income. The trade balance [HIGH] is the total value of exported goods minus imported goods. The services balance [MEDIUM] is the total value of exported services minus imported services. Primary income [MEDIUM] consists of factor income receipts and payments, including earnings from wages, interest, profits, and dividends. Secondary income / current transfers [MEDIUM] refers to one-way transfers of income where no good, service, or factor input is provided in return (such as foreign aid, remittances, and government grants).

A current account surplus [HIGH] occurs when total current account credit inflows exceed debit outflows. A current account deficit [HIGH] occurs when total current account debit outflows exceed credit inflows.

The capital account [BASIC] records capital transfers and transactions in non-produced, non-financial assets (such as patents or land rights). The financial account [HIGH] records cross-border transactions involving financial assets and liabilities, including direct investment, portfolio investment, and changes in reserve assets. Foreign direct investment (FDI) [MEDIUM] is an investment made by a firm or individual in physical assets or business operations in another country with lasting management control (typically 10% or more of voting stock). Portfolio investment [MEDIUM] refers to cross-border investments in debt or equity securities (such as stocks and bonds) without active management control. Errors and omissions [BASIC] is a balancing item used to offset net statistical discrepancies across BOP accounts.

BOP Relationship:

Under a floating exchange rate, the overall balance of payments must sum to zero mathematically:

$\text{Current Account} + \text{Capital Account} + \text{Financial Account} + \text{Net Errors and Omissions} = 0$

Consequently, a current account deficit must be offset by net inflows in the financial/capital accounts or a draw-down of official reserve assets. A persistent current account deficit is not inherently detrimental; its sustainability depends on the underlying causes, financing sources, whether borrowed funds finance productive investment, national debt levels, and foreign investor confidence.

Causes of a Current Account Deficit:

Strong domestic income growth driving high import demand.
Low export competitiveness due to structural economic inefficiencies.
High relative domestic inflation rates.
Overvalued domestic exchange rate.
Depressed economic growth in major export trading partner markets.
Structural reliance on foreign energy or capital inputs.

Correction Policies and Evaluation:

Expenditure-reducing policies: Contractionary fiscal or monetary policy reduces aggregate demand and import spending. Evaluation: Reduces national output and raises cyclical unemployment.
Expenditure-switching policies: Protectionist trade barriers or currency devaluation/depreciation shift domestic demand toward home-produced goods. Evaluation: Devaluation causes imported inflation; trade barriers risk foreign retaliation and domestic production inefficiencies.
Supply-side policies: Structural reforms enhance long-run productivity, quality, and price competitiveness. Evaluation: Involves significant time lags before export capacity improves.

4.7 Sustainable Development

Economic development [MEDIUM] is a broad, multidimensional process involving sustainable improvements in living standards, health outcomes, educational attainment, economic opportunity, self-esteem, and general quality of life. Sustainable development [HIGH] is development that meets the needs of the present generation without compromising the ability of future generations to meet their own needs. Economic growth [MEDIUM] is an increase in real output or real gross domestic product (GDP) produced by an economy over time.

Growth versus Development:

Growth is primarily quantitative, measuring increases in real economic output and aggregate income.
Development is qualitative and broader, encompassing living standards, health care, literacy, structural change, income distribution, institutional quality, and environmental sustainability.
Economic growth can provide the fiscal resources and market income necessary to support human development, but growth alone does not guarantee development if gains are unequally distributed or accompanied by environmental degradation.

4.8 Measuring Development

Gross National Income (GNI) per capita [MEDIUM] is gross national income divided by total population, representing average national income generated per person. Purchasing power parity (PPP) [HIGH] is an exchange rate adjustment mechanism that normalizes income figures by accounting for differences in domestic price levels and living costs across nations.

The Human Development Index (HDI) [HIGH] is a composite development indicator compiled by the United Nations, combining health (life expectancy at birth), education (mean years of schooling and expected years of schooling), and standard of living (GNI per capita adjusted for PPP).

The Multidimensional Poverty Index (MPI) [MEDIUM] is a composite indicator that measures acute poverty by evaluating non-monetary deprivations directly experienced by households across health, education, and living standards.

Limitations of Development Indicators:

Single income indicators like GDP or GNI per capita obscure income inequality, gender disparities, non-market transactions, informal economic activity, and negative environmental externalities.
Composite indices like the HDI compress complex, multidimensional development realities into single numerical ranks and rely on arbitrary indicator weightings.
National averages fail to capture regional, ethnic, or socioeconomic disparities within countries.
PPP calculations rely on standard international consumer baskets that may not accurately reflect local consumption patterns or quality differences.

4.9 Barriers to Economic Growth and Development

A poverty cycle / poverty trap [HIGH] is a self-reinforcing mechanism in which low national or individual income leads to low savings, which limits capital investment, resulting in low labor productivity and low future income.

Economic Barriers:

Low domestic savings and inadequate investment capital.
Poorly developed physical infrastructure (energy, transport, communications).
Low human capital development (education and health care deficits).
Primary commodity dependence and price volatility.
Inadequate access to commercial credit and banking systems.
High foreign debt burdens and debt-servicing costs.
Extreme income inequality and wealth concentration.
Weak tax systems and narrow revenue bases.
Large informal sectors reducing regulatory and tax capture.

Institutional and Political Barriers:

Weak or insecure property rights.
Pervasive public and private sector corruption.
Political instability and risk of civil conflict.
Bureaucratic inefficiency and weak rule of law.
Institutionalized discrimination against women or minority groups.

Social Barriers:

High disease burdens and inadequate healthcare delivery systems.
Low literacy levels and unequal educational access.
Rapid population growth and unfavorable demographic dependencies.

Poverty Cycle Chain:

$\text{Low Income} \rightarrow \text{Low Savings} \rightarrow \text{Low Investment} \rightarrow \text{Low Capital Accumulation \& Productivity} \rightarrow \text{Low Income}$

Development policies aim to break this cycle by financing investments in human capital, physical infrastructure, institutional capacity, microcredit access, and technology adoption.

4.10 Growth and Development Strategies

Trade liberalisation [MEDIUM] is the reduction or elimination of government restrictions on foreign trade, including tariffs, quotas, and non-tariff barriers. Export promotion [MEDIUM] is a growth strategy focused on expanding export sectors through subsidies, industrial policies, and competitive exchange rates to achieve outward-oriented growth. Import substitution [BASIC] is an inward-looking strategy aimed at replacing imported manufactured goods with domestic production behind protective trade barriers. Diversification [HIGH] is the policy of expanding the range of goods, services, and sectors within an economy to diminish dependence on primary commodities and reduce vulnerability to external shocks. A social enterprise [BASIC] is a revenue-generating business structure established primarily to accomplish social or environmental goals rather than maximize private profit.

A market-oriented strategy [MEDIUM] relies primarily on free market mechanisms, price signals, private enterprise, deregulation, and minimal state intervention to drive economic progress. An interventionist strategy [HIGH] relies on active government policies, public spending, industrial policy, infrastructure investments, and state redistribution to correct market failures and achieve development goals. Microfinance [MEDIUM] provides small-scale financial services, particularly microcredit loans, to low-income individuals and entrepreneurs who lack access to conventional banking services.

Foreign aid [MEDIUM] refers to capital, goods, or technical assistance transferred from international donors to developing countries on concessional terms. Official development assistance (ODA) [BASIC] consists of government-administered aid provided by developed nations or multilateral institutions explicitly designed to promote economic development and welfare in developing nations.

Policy Tools:

Interventionist tools: Public spending on education, healthcare, infrastructure, targeted industrial policy, subsidised credit, progressive tax redistribution, and legal reform.
Market-oriented tools: Deregulation, privatisation, trade liberalisation, foreign investment incentives, property rights enforcement, and tax reduction.

Foreign Direct Investment (FDI) Evaluation:

Potential benefits: Capital accumulation, job creation, technology transfer, managerial skill development, tax revenue generation, export diversification, and local industry integration.
Potential costs: Profit repatriation, local market power concentration, tax avoidance via transfer pricing, environmental degradation, labor exploitation, crowding out of domestic firms, and economic dependency.

Foreign Aid Evaluation:

Potential benefits: Fills domestic savings and foreign exchange gaps, funds essential social infrastructure, provides emergency humanitarian relief, and reduces extreme poverty.
Potential costs: Corruption risks, aid dependency, distortion of domestic market incentives, tied aid inefficiencies, and macroeconomic shocks (Dutch disease).

Best Evaluation Principle:

Development outcomes depend heavily on local country context. Effective strategy requires a balanced mix of market-oriented efficiency mechanisms and targeted interventionist state support to correct market failures while avoiding government failure.

Part II: Macroeconomics

3.1 Measuring Economic Activity and Its Variations

National income [MEDIUM] is the total monetary flow of income accrued by factor inputs in producing net output within an economy over a given period.

Gross domestic product (GDP) [HIGH] is the total market value of all final goods and services produced within a country's national borders during a given period (usually one year).

$\text{GDP} = C + I + G + (X - M)$

Gross national income (GNI) [HIGH] is the total income earned by a nation's residents, regardless of where the underlying factor inputs are geographically located.

$\text{GNI} = \text{GDP} + \text{net income from abroad}$

Nominal GDP [HIGH] measures gross domestic product using current market prices, without adjusting for price level inflation or deflation. Real GDP [HIGH] measures domestic output using constant prices from a designated base year, thereby removing the effects of price level changes.

The GDP deflator [HIGH] is a broad economic price index used to convert nominal GDP into real GDP, reflecting changes in the price level of domestically produced goods and services.

$\text{GDP deflator} = \left( \frac{\text{Nominal GDP}}{\text{Real GDP}} \right) \times 100$

$\text{Real GDP} = \left( \frac{\text{Nominal GDP}}{\text{GDP deflator}} \right) \times 100$

Gross domestic product per capita [HIGH] is national GDP divided by total population, measuring output generated per person.

$\text{GDP per capita} = \frac{\text{GDP}}{\text{population}}$

Purchasing power parity (PPP) [HIGH] adjusts national income figures to equalize the purchasing power of different currencies by accounting for regional price level differences.

Nominal vs. Real Distinction:

Nominal values change whenever physical output or general market prices fluctuate. Real values isolate changes in physical volume by removing price level distortions, making real measures essential for comparing economic output over time. Per capita metrics adjust for population changes, and PPP adjustments permit meaningful cross-country living standard comparisons.

The business cycle [HIGH] describes recurring short-run fluctuations in real GDP around an economy's long-term trend path or potential output. Potential output [HIGH] is the maximum sustainable level of real output an economy can produce when all factor inputs are fully employed at their normal utilization rates without generating inflationary pressure. An output gap [HIGH] is the percentage or dollar difference between actual real GDP and potential output.

Business Cycle Phases:

$\text{Expansion} \rightarrow \text{Peak} \rightarrow \text{Contraction / Recession} \rightarrow \text{Trough} \rightarrow \text{Recovery}$

$\text{Real GDP growth rate} = \left( \frac{\text{Real GDP}_{\text{new}} - \text{Real GDP}_{\text{old}}}{\text{Real GDP}_{\text{old}}} \right) \times 100$

Limitations of GDP as a Measure of Well-Being:

Ignores income distribution and socioeconomic inequality.
Excludes non-market production, household production, and unpaid volunteer work.
Fails to record informal or shadow economy transactions.
Ignores environmental degradation, resource depletion, and negative externalities.
Ignores changes in leisure time, working conditions, and quality of life.
Treats expenditures on disaster recovery or defensive health care as positive additions to output.

3.2 Aggregate Demand and Aggregate Supply

Aggregate demand (AD) [HIGH] is the total planned expenditure on domestically produced final goods and services at various average price levels over a given period.

$\text{AD} = C + I + G + (X - M)$

Why the Aggregate Demand Curve Slopes Downward:

Real wealth / real-balance effect: A lower price level increases the real purchasing power of accumulated household monetary wealth, encouraging higher consumption expenditure ( $C$ ).
Interest-rate effect: A lower price level reduces money demand, driving down nominal interest rates, which lowers borrowing costs and stimulates investment ( $I$ ) and durable consumption ( $C$ ).
International-trade effect: A lower domestic price level relative to foreign countries makes exports more price-competitive and imports relatively more expensive, raising net exports ( $X - M$ ).

Determinants of Aggregate Demand Shifts:

Consumption ( $C$ ): Disposable income, consumer confidence, wealth, real interest rates, household indebtedness, personal income tax rates.
Investment ( $I$ ): Business confidence, expected real demand, interest rates, corporate tax rates, technological change, state of capital stocks.
Government spending ( $G$ ): Political policy priorities, fiscal policy stance, discretionary social spending, infrastructure commitments.
Net exports ( $X - M$ ): Foreign national income, exchange rate shifts, trade policy, relative international price competitiveness.

Short-run aggregate supply (SRAS) [HIGH] represents total domestic output produced by firms at different price levels when input prices—especially nominal wages—remain fixed.

Determinants of SRAS Shifts:

Changes in resource and wage costs.
Changes in business indirect taxes or government production subsidies.
Import cost adjustments (imported raw material prices).
Economy-wide supply shocks (e.g., natural disasters, geopolitical disruptions).

Macroeconomic equilibrium [HIGH] occurs where aggregate demand equals aggregate supply, establishing equilibrium real GDP and price level.

A recessionary / deflationary gap [HIGH] occurs when equilibrium real GDP is below potential output ( $Y < Y_p$ ), characterized by high cyclical unemployment and idle productive capacity. An inflationary gap [HIGH] occurs when equilibrium real GDP exceeds potential output ( $Y > Y_p$ ), driving unemployment below its natural rate and creating upward pressure on prices.

Long-run aggregate supply (LRAS) [HIGH] represents the economy's potential output when all resource prices and wages are fully flexible.

Monetarist / New Classical Model:

LRAS is vertical at potential output ( $Y_p$ ).
Wages and resource prices are fully flexible in the long run, automatically self-correcting output gaps back to full employment.
Demand-side shifts only affect real output in the short run; in the long run, sustained increases in $AD$ result solely in higher price levels.

Keynesian Aggregate Supply Model [HIGH]:

Represents aggregate supply as a single curve with three distinct sections: a horizontal (flat) section indicating significant spare capacity where $AD$ increases output without inflation; an upward-sloping section where capacity constraints emerge and both output and prices rise; and a vertical section at full capacity ( $Y_p$ ).
Wages and prices are sticky downward, allowing recessionary gaps to persist indefinitely without self-correction, justifying discretionary demand-management interventions.

A supply shock [MEDIUM] is an unexpected exogenous event that significantly alters firms' production costs, shifting the SRAS curve. Stagflation [HIGH] is the simultaneous occurrence of persistent inflation, falling or stagnant real output, and high unemployment, typically caused by an adverse supply shock.

Diagrams to know for this section:

AD shifts right/left on a standard price level vs. real GDP graph.
SRAS shifts right/left, including adverse supply shocks causing stagflation.
Monetarist / New Classical model showing short-run and long-run adjustments to recessionary and inflationary gaps.
Keynesian AS curve showing equilibrium below, near, and at full employment.
Long-run economic growth represented by rightward shifts of vertical LRAS or Keynesian AS.

3.3 Macroeconomic Objectives

Unemployment [HIGH] is a state in which individuals of working age who are without work, available for work, and actively seeking employment cannot find jobs. The labour force [HIGH] comprises all employed persons plus all unemployed individuals actively seeking work.

$\text{Unemployment rate} = \left( \frac{\text{Unemployed}}{\text{Labour force}} \right) \times 100$

The natural rate of unemployment [HIGH] is the unemployment rate present when the economy produces at potential output, consisting of structural, frictional, and seasonal unemployment.

Structural unemployment [HIGH] arises from a mismatch between the skills or locations of unemployed workers and the requirements of available job vacancies, often driven by structural economic shifts or technological automation. Frictional unemployment [MEDIUM] is short-term unemployment experienced by individuals who are between jobs or entering the labor market. Seasonal unemployment [MEDIUM] results from predictable seasonal variations in labor demand in specific industries. Cyclical / demand-deficient unemployment [HIGH] occurs during economic downturns when aggregate demand falls below full-employment levels.

Policy Match for Unemployment Types:

Cyclical unemployment $\rightarrow$ Expansionary monetary or fiscal policy.
Structural unemployment $\rightarrow$ Supply-side policy: occupational retraining programs, educational reform, labor mobility incentives, job matching centers.
Frictional unemployment $\rightarrow$ Improved job market information systems and employment search platforms.
Seasonal unemployment $\rightarrow$ Off-season employment programs, information dissemination, and geographic mobility grants.

Inflation [HIGH] is a sustained, economy-wide increase in the general price level of goods and services over time. The Consumer Price Index (CPI) [HIGH] measures the cost of a representative basket of goods and services consumed by a typical urban household relative to a chosen base year.

$\text{CPI} = \left( \frac{\text{Cost of basket in current year}}{\text{Cost of basket in base year}} \right) \times 100$

$\text{Inflation rate} = \left( \frac{\text{CPI}_{\text{new}} - \text{CPI}_{\text{old}}}{\text{CPI}_{\text{old}}} \right) \times 100$

Deflation [HIGH] is a sustained decrease in the general price level (negative inflation rate). Disinflation [HIGH] is a decrease in the rate of inflation, where the price level continues to rise but at a slower rate.

Demand-pull inflation [HIGH] is inflation caused by an increase in aggregate demand, particularly as the economy approaches full employment. Cost-push inflation [HIGH] is inflation driven by increases in production costs (e.g., wages, raw materials), which shift SRAS to the left.

Costs of Inflation:

Loss of real purchasing power for fixed-income earners.
Greater economic uncertainty, chilling long-term investment.
Arbitrary redistribution of wealth from lenders to borrowers.
Reduced global export price competitiveness.
Menu costs and shoe-leather costs.
Distorted price signals in free markets.

Costs of Deflation:

Deferred consumption as consumers anticipate lower future prices.
Increasing real burden of private and public debt.
Falling corporate profits and increased risk of bankruptcies.
Deepening cyclical unemployment and persistent recessionary spirals.
Reduced monetary policy effectiveness (liquidity traps).

The short-run Phillips curve [MEDIUM] illustrates an inverse relationship between inflation and unemployment in the short run. The long-run Phillips curve [MEDIUM] is vertical at the natural rate of unemployment, showing that no permanent inflation-unemployment trade-off exists in the long run.

Economic growth [HIGH] is an increase in real economic output over time, measured as the percentage growth rate of real GDP. Actual / short-run growth [HIGH] refers to increases in actual real GDP produced by absorbing spare capacity. Potential / long-run growth [HIGH] refers to an expansion of the economy's productive capacity, represented by rightward shifts in LRAS or PPC curves.

Long-run growth drivers include quantitative and qualitative expansions of land, labor, physical capital, human capital, technology, and institutional quality. Benefits include higher average living standards, increased employment, expanded government tax revenues, and lower poverty rates. Costs include negative environmental externalities, resource depletion, structural unemployment, and increased inequality if gains are unevenly distributed.

A budget deficit [HIGH] occurs when total government expenditures exceed total tax revenues in a fiscal year. A budget surplus [MEDIUM] occurs when government tax revenues exceed expenditures. Government / national debt [HIGH] is the cumulative sum of outstanding financial obligations owed by a government resulting from past budget deficits.

$\text{Debt-to-GDP ratio} = \left( \frac{\text{Government debt}}{\text{GDP}} \right) \times 100$

Sustainable government debt [MEDIUM] describes a debt level that a sovereign state can service without defaulting or requiring economically damaging spending cuts or tax hikes.

Macroeconomic Objective Conflicts:

Low unemployment vs. low inflation: Expansionary policies to reduce cyclical unemployment can increase aggregate demand, causing demand-pull inflation.
Economic growth vs. environmental sustainability: Higher output can increase resource depletion, carbon emissions, and pollution.
Economic growth vs. income equality: Fast market-led growth may disproportionately benefit capital owners, exacerbating income disparities.
Inflation control vs. short-run output: Contractionary policies to curb inflation reduce real GDP and increase unemployment in the short run.

3.4 Economics of Inequality and Poverty

Income [MEDIUM] is a flow of money earned over a period, such as wages, dividends, interest, or rent. Wealth [MEDIUM] is the total stock of economic assets owned by an individual or household at a specific point in time, net of liabilities. Economic inequality [HIGH] refers to disparities in the distribution of income or wealth across individuals or groups within a society.

The Lorenz curve [HIGH] is a graphical representation showing the cumulative percentage of national income earned by cumulative percentages of the population. The Gini coefficient [HIGH] is a summary statistical measure of inequality derived from the Lorenz curve, ranging from 0 (perfect equality) to 1 (absolute inequality).

$\text{Gini coefficient} = \frac{\text{Area between 45-degree line of equality and Lorenz curve}}{\text{Total area beneath 45-degree line of equality}}$

Absolute poverty [HIGH] is a condition where household income falls below a minimum level required to secure basic human survival needs (food, clean water, shelter). Relative poverty [HIGH] is a condition where household income falls below a relative threshold set in relation to average national income standards (e.g., below 50% of median national income). A poverty line [MEDIUM] is an explicit threshold income level used by governments or international institutions to measure poverty headcount ratios.

Causes of inequality and poverty include unequal distribution of ownership of capital assets, educational gaps, labor market discrimination, structural technological shifts, tax structures, and unequal opportunity.

A progressive tax [HIGH] is a tax structure where the average tax rate increases as income increases. A proportional tax [MEDIUM] is a tax structure where the average tax rate remains constant across all income levels. A regressive tax [HIGH] is a tax structure where the average tax rate falls as income increases.

A direct tax [MEDIUM] is a tax imposed directly on income, profits, or wealth (e.g., income tax, corporate tax). A transfer payment [HIGH] is a non-reciprocal payment made by the government to individuals without any corresponding exchange of goods or services (e.g., unemployment benefits, pensions). Universal basic income (UBI) [BASIC] is an unconditional, regular monetary payment provided by the government to all citizens regardless of income or employment status.

Policies to Reduce Inequality and Poverty:

Progressive taxation systems.
Targeted social safety net transfer payments.
Universal public provision of merit goods (healthcare and education).
Statutory minimum wage legislation.
Investments in human capital and active labor market training.
Anti-discrimination laws and equal opportunity initiatives.

3.5 Demand Management - Monetary Policy

Monetary policy [HIGH] is discretionary demand-management policy executed by a central bank involving interest rate adjustments and credit conditions to influence aggregate demand and macroeconomic objectives.

A central bank [HIGH] is the national institution responsible for issuing currency, managing official reserves, acting as banker to the government and lender of last resort, and administering monetary policy. Money creation [HIGH] is the process by which commercial banks create new demand deposits by lending out excess reserves. The required reserve ratio [MEDIUM] is the legally mandated percentage of customer deposits that commercial banks must hold in reserve and cannot lend out.

$\text{Simple money multiplier} = \frac{1}{\text{Required reserve ratio}}$

Bank Money Creation Chain:

$\text{Initial Deposit} \rightarrow \text{Bank Holds Required Reserves} \rightarrow \text{Bank Lends Excess Reserves} \rightarrow \text{Loan Deposited in Second Bank} \rightarrow \text{Process Repeats}$

Nominal interest rate [MEDIUM] is the interest rate stated in unadjusted percentage terms. Real interest rate [HIGH] is the interest rate adjusted to account for expected or actual inflation.

$\text{Real interest rate} \approx \text{Nominal interest rate} - \text{Inflation rate}$

Expansionary monetary policy [HIGH] involves lowering central bank policy interest rates or easing financial conditions to stimulate aggregate demand.

Transmission Mechanism for Expansionary Monetary Policy:

Central bank cuts policy rate $\rightarrow$ Market commercial interest rates fall $\rightarrow$ Cost of borrowing decreases while incentive to save falls $\rightarrow$ Household consumption ( $C$ ) and firm investment ( $I$ ) increase $\rightarrow$ Aggregate demand ( $AD$ ) shifts rightward $\rightarrow$ Real GDP increases, cyclical unemployment falls, and demand-pull inflationary pressure increases.

Contractionary monetary policy [HIGH] involves raising central bank interest rates to constrain aggregate demand and reduce inflation.

Transmission Mechanism for Contractionary Monetary Policy:

Central bank raises policy rate $\rightarrow$ Commercial lending rates increase $\rightarrow$ Borrowing becomes more expensive and saving yields higher returns $\rightarrow$ $C$ and $I$ decline $\rightarrow$ $AD$ shifts leftward $\rightarrow$ Inflationary pressure decreases, but real GDP growth slows and unemployment may temporarily rise.

Open market operations [MEDIUM] involve the central bank buying or selling government bonds to adjust commercial bank reserves and short-term market liquidity. Quantitative easing (QE) [MEDIUM] is an unconventional expansionary monetary policy where a central bank purchases large quantities of longer-term financial assets from secondary markets using created central bank reserves to boost money supply, lower long-term interest rates, and encourage bank lending.

Strengths of Monetary Policy:

Ability to make frequent, incremental interest rate adjustments.
Short implementation lag compared to fiscal policy.
Political independence of central banks insulates decisions from election cycles.
Reversibility of decisions.

Limitations of Monetary Policy:

Transmission mechanism time lags (often 12–18 months).
Reduced effectiveness during severe recessions when consumer and business confidence is depressed (pushing on a string).
Nominal lower bound constraints (zero lower bound).
Potential to generate asset price bubbles or destabilize foreign exchange rates.

3.6 Demand Management - Fiscal Policy

Fiscal policy [HIGH] is the discretionary use of government spending and taxation to influence aggregate demand and stabilize the macroeconomy.

Expansionary fiscal policy [HIGH] involves increasing government spending ( $G$ ), cutting taxes ( $T$ ), or both, to raise aggregate demand. Contractionary fiscal policy [HIGH] involves decreasing government spending, increasing taxes, or both, to reduce aggregate demand.

Transmission Mechanism for Expansionary Fiscal Policy:

Government increases spending ( $G$ ) directly or cuts personal/corporate taxes ( $T$ ) $\rightarrow$ Disposable income rises, stimulating consumption ( $C$ ) and investment ( $I$ ) $\rightarrow$ Aggregate demand ( $AD$ ) shifts rightward $\rightarrow$ Real output increases and cyclical unemployment falls; budget deficit increases.

Automatic stabilisers [HIGH] are institutionally embedded fiscal mechanisms that automatically offset economic fluctuations without explicit government intervention. Key examples include progressive income taxes and income-tested social welfare transfers. During recessions, tax collections fall and welfare payouts rise, cushioning aggregate demand. During expansions, tax collections rise and welfare payouts fall, dampening inflationary pressures.

Crowding out [HIGH] occurs when expansionary fiscal policy financed by government borrowing increases market interest rates, thereby reducing private sector investment spending.

Strengths of Fiscal Policy:

Direct impact of government spending ( $G$ ) on aggregate demand.
Ability to target specific economic sectors or regions.
Effective in deep recessions when monetary policy is constrained.
Capital expenditure investments expand long-run productive capacity.

Limitations of Fiscal Policy:

Significant recognition, implementation, and impact time lags.
Political constraints and election-cycle spending pressures.
Accumulation of public debt and rising debt-servicing burdens.
Risk of crowding out private investment.
Difficulties in accurately fine-tuning macroeconomic variables.

The Keynesian Multiplier [HIGH] demonstrates that an initial change in autonomous expenditure leads to a larger final change in national income.

Definitions:

Marginal Propensity to Consume (MPC) [HIGH]: The fraction of additional disposable income spent on domestic consumption.
Marginal Propensity to Save (MPS) [HIGH]: The fraction of additional income saved.
Marginal Propensity to Tax (MPT) [MEDIUM]: The fraction of additional income paid in taxes.
Marginal Propensity to Import (MPM) [MEDIUM]: The fraction of additional income spent on imports.

$\text{MPC} + \text{MPS} + \text{MPT} + \text{MPM} = 1$

$k = \frac{1}{1 - \text{MPC}} = \frac{1}{\text{MPS} + \text{MPT} + \text{MPM}}$

$\Delta \text{Real GDP} = k \times \Delta \text{Autonomous Spending}$

Why the Multiplier Works:

An initial injection represents income for recipients, who spend a portion equal to the MPC. That spending becomes income for another set of individuals, generating continuous, diminishing rounds of spending. Leakages ( $MPS + MPT + MPM$ ) reduce the magnitude of spending in each subsequent round.

3.7 Supply-Side Policies

Supply-side policies [HIGH] are government measures designed to expand the productive capacity of the economy by increasing the quantity or quality of factors of production, shifting the LRAS or Keynesian AS curve to the right.

Market-based supply-side policies [HIGH] seek to enhance long-run productive capacity by lowering taxes, removing market rigidities, strengthening incentives, and unleashing competitive forces.

Main Market-Based Measures:

Tax reductions: Lowering personal income tax to incentivize labor participation, and cutting corporate tax to stimulate private investment.
Labour market reforms: Reducing trade union power, lowering minimum wages, decreasing unemployment benefit duration to increase job search incentives, and enhancing hiring/firing flexibility.
Deregulation [MEDIUM]: Removing government regulations to reduce compliance costs for private enterprise.
Privatisation [MEDIUM]: Transferring state-owned enterprises into private ownership to improve productive efficiency.
Encouraging free trade and market competition.

Interventionist supply-side policies [HIGH] involve direct government public expenditure and targeted programs designed to correct market failures and enhance human and physical capital.

Main Interventionist Measures:

Human capital investment: Spending on education, vocational training, and public healthcare.
Infrastructure investment: Public financing of transportation, energy, and digital networks.
Research and development (R&D) support: Direct public research grants or tax credits for private innovation.
Industrial policy: Targeted support for nascent strategic industries.

Advantages and Disadvantages of Supply-Side Policies:

Supply-side policies expand potential output ( $Y_p$ ), support long-run economic growth, create structural employment, and ease inflationary pressure. However, interventionist policies impose significant fiscal costs and carry risks of government failure. Market-based policies can worsen income inequality, undermine environmental protection, and reduce employment security. Additionally, all supply-side policies involve long implementation time lags.

Macro Policy Matching Summary Grid:

Recessionary gap / cyclical unemployment $\rightarrow$ Expansionary monetary or fiscal policy.
Demand-pull inflation $\rightarrow$ Contractionary monetary or fiscal policy.
Structural unemployment $\rightarrow$ Supply-side intervention (education, retraining, structural reform).
Cost-push inflation $\rightarrow$ Supply-side measures targeting resource costs; demand reduction lowers price level but worsens output.
Long-run economic growth $\rightarrow$ Interventionist and market-based supply-side policies.

Part III: Microeconomics

2.1 Demand

Demand [HIGH] is the quantity of a good or service that consumers are willing and able to purchase at various prices over a given period, ceteris paribus. Quantity demanded [MEDIUM] is the specific quantity consumers are willing and able to purchase at a specific price. The law of demand [HIGH] states that as price increases, quantity demanded falls, and as price decreases, quantity demanded rises, ceteris paribus. Ceteris paribus [HIGH] is the assumption that all other external variables remain constant.

The real income effect [MEDIUM] explains that a price drop increases consumers' real purchasing power, enabling them to buy more. The substitution effect [MEDIUM] explains that a price drop makes a good relatively cheaper compared to alternative substitutes, encouraging consumers to substitute toward it.

Movement versus Shift Rule:

A change in the good's own price causes a movement along the existing demand curve (a change in quantity demanded).
A change in any non-price determinant shifts the entire demand curve (a change in demand).

A normal good [HIGH] is a good whose demand rises as consumer income increases ( $YED > 0$ ). An inferior good [HIGH] is a good whose demand falls as consumer income increases ( $YED < 0$ ). Substitute goods [HIGH] are goods used in place of one another; an increase in the price of one leads to an increase in demand for the other. Complementary goods [HIGH] are goods consumed together; an increase in the price of one leads to a decrease in demand for the other.

Non-Price Determinants of Demand:

Consumer disposable income.
Tastes, preferences, and social trends.
Population size and demographic shifts.
Prices of substitute and complementary goods.
Consumer price and economic expectations.

2.2 Supply

Supply [HIGH] is the quantity of a good or service that producers are willing and able to offer for sale at various prices over a given period, ceteris paribus. Quantity supplied [MEDIUM] is the specific quantity producers are willing and able to offer for sale at a specific price. The law of supply [HIGH] states that as price rises, quantity supplied increases, and as price falls, quantity supplied decreases, ceteris paribus.

Movement versus Shift Rule:

A change in own price causes a movement along the existing supply curve (change in quantity supplied).
A change in any non-price determinant shifts the entire supply curve (change in supply).

Non-Price Determinants of Supply:

Costs of factors of production (wages, raw materials, energy).
State of technology and productive efficiency.
Business indirect taxes imposed or subsidies granted by governments.
Number of competing firms in the industry.
Producer price expectations.
Prices of related products in production (joint or competitive supply).
Exogenous physical shocks (e.g., weather, natural disasters).

2.3 Competitive Market Equilibrium

Market equilibrium [HIGH] is the state in which quantity demanded equals quantity supplied ( $Q_d = Q_s$ ), establishing an equilibrium price ( $P_e$ ) and quantity ( $Q_e$ ).

An excess demand / shortage [HIGH] occurs when quantity demanded exceeds quantity supplied at the current market price ( $P < P_e$ ), putting upward pressure on price. An excess supply / surplus [HIGH] occurs when quantity supplied exceeds quantity demanded at the current market price ( $P > P_e$ ), putting downward pressure on price.

The price mechanism [HIGH] refers to the process by which market price adjustments reallocate resources in response to supply and demand forces.

Functions of the Price Mechanism:

Signalling function: Prices convey information to buyers and sellers regarding relative market scarcity.
Incentive function: High prices signal high profitability, incentivizing producers to reallocate resources toward production.
Rationing function: Prices ration limited goods among consumers willing and able to pay.

Consumer surplus [HIGH] is the difference between the maximum price consumers are willing to pay for a good and the market price actually paid. Producer surplus [HIGH] is the difference between the market price producers receive and the minimum price they would accept to supply the good. Social / community surplus [HIGH] is the sum of consumer surplus and producer surplus.

Allocative efficiency [HIGH] is the resource allocation that maximizes social surplus. In competitive markets without externalities, allocative efficiency occurs where marginal benefit equals marginal cost ( $MB = MC$ ) or marginal social benefit equals marginal social cost ( $MSB = MSC$ ).

2.4 Critique of Maximising Behaviour

Rational consumer behaviour [MEDIUM] assumes that consumers systematically allocate income to maximize overall utility subject to budget constraints. Utility [MEDIUM] is the measure of satisfaction or benefit derived from consuming a good or service. Rational producer behaviour [MEDIUM] assumes that firms make output decisions to maximize profit.

$\text{Profit} = \text{Total Revenue} - \text{Total Cost}$

Bounded rationality [MEDIUM] states that consumers' capacity for rational decision-making is restricted by limited cognitive capacity, incomplete information, and time constraints. Behavioural economics [MEDIUM] studies how psychological, cognitive, and social biases cause systematically irrational economic decisions.

Choice architecture [BASIC] refers to the design of decision-making environments to influence choices. A nudge [MEDIUM] is an intervention in choice architecture that alters behavior predictably without prohibiting options or significantly altering economic incentives.

2.5 Elasticities of Demand

Price elasticity of demand (PED) [HIGH] measures the responsiveness of quantity demanded to a change in own price, ceteris paribus.

$\text{PED} = \frac{\% \Delta Q_d}{\% \Delta P}$

Elasticity Classifications:

Price-elastic demand: $|\text{PED}| > 1$ (percentage change in $Q_d$ > percentage change in $P$ ).
Price-inelastic demand: $|\text{PED}| < 1$ (percentage change in $Q_d$ < percentage change in $P$ ).
Unitary elasticity: $|\text{PED}| = 1$ .
Perfectly inelastic demand: $\text{PED} = 0$ (vertical demand curve).
Perfectly elastic demand: $\text{PED} = \infty$ (horizontal demand curve).

Determinants of PED:

Availability and closeness of substitute goods.
Degree of necessity vs. luxury.
Proportion of income spent on the good.
Time period available for adjustment.

Total revenue (TR) [HIGH] is the total monetary receipt generated by a firm from selling output.

$\text{TR} = P \times Q$

PED and Total Revenue Relationships:

Elastic demand ( $|\text{PED}| > 1$ ): Price cuts increase total revenue; price increases decrease total revenue.
Inelastic demand ( $|\text{PED}| < 1$ ): Price cuts reduce total revenue; price increases increase total revenue.
Unit elastic demand ( $|\text{PED}| = 1$ ): Price changes leave total revenue unchanged.

Income elasticity of demand (YED) [HIGH] measures the responsiveness of demand to changes in consumer income, ceteris paribus.

$\text{YED} = \frac{\% \Delta Q_d}{\% \Delta \text{Income}}$

Classification:

Normal goods: $\text{YED} > 0$ .
Inferior goods: $\text{YED} < 0$ .
Income-inelastic normal goods (necessities): $0 < \text{YED} < 1$ .
Income-elastic normal goods (luxuries): $\text{YED} > 1$ .

Practical Applications:

Firms use PED to optimize pricing strategies and total revenue. Governments rely on PED to forecast tax yields and market responses when setting indirect tax rates. YED helps businesses anticipate demand trends across economic cycles and explains long-run structural shifts toward service industries as incomes grow.

2.6 Elasticity of Supply

Price elasticity of supply (PES) [HIGH] measures the responsiveness of quantity supplied to a change in price, ceteris paribus.

$\text{PES} = \frac{\% \Delta Q_s}{\% \Delta P}$

Elasticity Classifications:

Elastic supply: $\text{PES} > 1$ .
Inelastic supply: $\text{PES} < 1$ .
Unitary elastic supply: $\text{PES} = 1$ .
Perfectly inelastic supply: $\text{PES} = 0$ (vertical supply curve).
Perfectly elastic supply: $\text{PES} = \infty$ (horizontal supply curve).

Determinants of PES:

Amount of spare capacity available.
Mobility of factor inputs.
Time horizon available to adjust production processes.
Ease and cost of inventory storage.
Length and complexity of the production process.

Key Principle: Supply is more price-elastic in the long run than in the short run because firms can adjust physical capital, factory capacity, and production technology.

2.7 Role of Government in Microeconomics

A price ceiling / maximum price [HIGH] is a legally mandated upper price limit that sellers cannot exceed; to be binding, it must be set below the market equilibrium price.

Effects of a Binding Price Ceiling:

Creates a permanent shortage ( $Q_d > Q_s$ ), leading to non-price rationing mechanisms (queues, rationing coupons), underground black markets, reduced producer revenues, lower quality, and allocative inefficiency.

A price floor / minimum price [HIGH] is a legally mandated lower price limit below which transactions cannot occur; to be binding, it must be set above the market equilibrium price.

Effects of a Binding Price Floor:

Creates a permanent market surplus ( $Q_s > Q_d$ ). In agricultural markets, governments may buy surplus output. In labor markets, a minimum wage set above equilibrium can increase excess labor supply (unemployment), depending on market structure.

A minimum wage [HIGH] is a legally established price floor in the labor market. An indirect tax [HIGH] is a tax imposed on expenditure, collected by sellers and remitted to the government. A specific tax [HIGH] is a fixed dollar amount imposed per unit sold. An ad valorem tax [MEDIUM] is a proportional tax charged as a percentage of the retail price.

Tax incidence [HIGH] refers to the distribution of the economic tax burden between consumers and producers.

Tax Incidence Rule:

The tax burden falls more heavily on the less price-elastic side of the market. If demand is price-inelastic relative to supply, consumers bear most of the tax burden; if supply is inelastic relative to demand, producers bear most of the tax.

$\text{Government tax revenue} = \text{tax per unit} \times Q_{\text{after tax}}$

A subsidy [HIGH] is a government payment to domestic producers that lowers per-unit production costs and encourages market output.

$\text{Government subsidy expenditure} = \text{subsidy per unit} \times Q_{\text{after subsidy}}$

Diagrams to know for this section:

Binding price ceiling below equilibrium showing shortage.
Binding price floor/minimum wage above equilibrium showing surplus/unemployment.
Specific and ad valorem indirect tax shifts, showing consumer price, producer receipt, tax revenue box, and deadweight loss.
Subsidy diagram showing downward supply shift, consumer savings, producer receipts, and total government cost.

2.8 Market Failure - Externalities and Common-Pool Resources

Market failure [HIGH] occurs when a competitive market fails to allocate resources efficiently, resulting in a net loss of social surplus.

An externality [HIGH] is a cost or benefit imposed on a third party not directly involved in the transaction, which is not reflected in market prices. Marginal private benefit (MPB) [HIGH] is the private benefit enjoyed by the consumer of an additional unit. Marginal private cost (MPC) [HIGH] is the private cost incurred by the producer of an additional unit. Marginal external benefit (MEB) [HIGH] is the third-party benefit from an additional unit. Marginal external cost (MEC) [HIGH] is the third-party cost from an additional unit. Marginal social benefit (MSB) [HIGH] is the total benefit to society from an additional unit ( $\text{MSB} = \text{MPB} + \text{MEB}$ ). Marginal social cost (MSC) [HIGH] is the total cost to society from an additional unit ( $\text{MSC} = \text{MPC} + \text{MEC}$ ).

Socially optimum output [HIGH] occurs where marginal social benefit equals marginal social cost ( $\text{MSB} = \text{MSC}$ ). Welfare loss [HIGH] represents the deadweight loss of social surplus resulting from misallocated resources.

Externalities Types and Conditions:

Negative production externality [HIGH]: $\text{MSC} > \text{MPC}$ ; market overproduces ( $Q_{\text{market}} > Q_{\text{social}}$ ).
Negative consumption externality [HIGH]: $\text{MSB} < \text{MPB}$ ; market overconsumes ( $Q_{\text{market}} > Q_{\text{social}}$ ).
Positive production externality [HIGH]: $\text{MSC} < \text{MPC}$ ; market underproduces ( $Q_{\text{market}} < Q_{\text{social}}$ ).
Positive consumption externality [HIGH]: $\text{MSB} > \text{MPB}$ ; market underconsumes ( $Q_{\text{market}} < Q_{\text{social}}$ ).

A demerit good [MEDIUM] is a good deemed socially harmful that is overconsumed due to imperfect consumer information or negative externalities. A merit good [MEDIUM] is a good deemed socially beneficial that is underconsumed due to imperfect information or positive externalities.

Policy Responses to Externalities:

Pigouvian taxes [MEDIUM] set equal to marginal external cost to internalise negative externalities.
Tradable permits [HIGH]: Cap-and-trade systems limiting total emissions while allowing firms to trade allowances.
State command-and-control regulation.
Production subsidies or direct state provision for positive externalities.
Information campaigns and consumer education.

A common-pool resource [HIGH] is a resource that is rivalrous in consumption but non-excludable. A good is rivalrous [HIGH] if one person's consumption reduces the quantity available to others. A good is non-excludable [HIGH] if it is impossible or prohibitively expensive to prevent non-payers from using it. The tragedy of the commons [HIGH] is the overexploitation and degradation of common-pool resources caused by individual self-interest without private market pricing.

2.9 Public Goods

A public good [HIGH] is a good that is both non-rivalrous and non-excludable in consumption. A non-rivalrous [HIGH] good can be consumed by one individual without reducing its availability to others. The free-rider problem [HIGH] occurs when rational individuals consume a non-excludable good without paying for it, creating market failure where private firms cannot profitably provide the good. A quasi-public good [MEDIUM] possesses some, but not all, characteristics of pure public goods (e.g., toll roads).

Why Public Goods Cause Market Failure:

Because public goods are non-excludable, private firms cannot charge users, leading to severe underprovision or total absence of private supply. Consequently, governments must provide public goods directly using general tax revenues.

2.10 Asymmetric Information

Asymmetric information [HIGH] occurs when one party to an economic transaction possesses more or better information than the other party.

Adverse selection [HIGH] is a pre-transaction information failure where hidden information leads to undesirable participants dominating the market (e.g., high-risk individuals dominating health insurance pools). Moral hazard [HIGH] is a post-transaction behavioral failure where an insured or protected party takes greater risks because another party bears the financial consequences.

Memory Line:

Adverse selection = hidden information before the transaction.
Moral hazard = opportunistic behavior after the transaction.

Remedies include mandatory information disclosure laws, market signaling, screening, warranties, and state regulation.

2.12 The Market's Inability to Achieve Equity

Equity [HIGH] is fairness or justice in the economic distribution of income and opportunity (a normative concept). Equality [MEDIUM] is the mathematical sameness in the distribution of economic outcomes.

Why Free Markets Fail to Achieve Equity:

Market-determined rewards depend on the initial ownership of productive assets, innate talents, accumulated skills, and institutional power. As a result, allocatively efficient markets can yield highly unequal and socially undesirable outcomes. Governments intervene using progressive taxes, social transfers, merit-good provision, minimum wage laws, and equal-opportunity regulations.

Final Rapid-Revision Pages

1. Formulas to Memorise

$\text{GDP} = C + I + G + (X - M)$

$\text{GNI} = \text{GDP} + \text{net factor income from abroad}$