Drawing and Interpreting Economics Diagrams (HSC SSCE Economics): Revision Notes

Drawing and Interpreting Economics Diagrams

Introduction to economic diagrams

Understanding and using economic diagrams is a fundamental skill in SSCE HSC Economics. These visual tools help us analyse complex economic relationships, predict market outcomes, and evaluate policy impacts. Some diagrams are explicitly required by the syllabus (such as foreign exchange market models), while others provide valuable frameworks for deeper understanding of economic concepts.

Economic diagrams serve two main purposes. First, they allow us to represent macroeconomic phenomena at the "big picture" level, showing how entire economies respond to changes. Second, they enable microeconomic analysis of specific markets and sectors. Mastering these diagrams will strengthen your ability to respond to stimulus-based questions and communicate economic ideas clearly.

International trade and protection

Impact of international organisations on protection levels

International organisations like the World Trade Organization (WTO), supported by the International Monetary Fund (IMF) and World Bank, work to reduce trade protection globally. The economic impact of tariff reductions can be analysed using supply and demand diagrams.

When tariffs are removed or reduced:

• The domestic price falls from the protected level ($P^T$) to the world price ($P^W$)
• Imports increase as foreign goods become relatively cheaper
• Domestic production contracts as import-competing firms face greater competition
• Consumer surplus increases due to lower prices and greater choice
• Some workers in import-competing industries may experience short-term unemployment

The diagram shows how removing protection shifts the economy from a higher domestic price (with tariff) to a lower world price. The quantity of imports increases substantially, shown by the expansion along the horizontal axis.

Trading bloc agreements and subsidies

Trading blocs have more complex effects on global trade. Some, like APEC, aim to reduce tariffs for all trading partners. Others, like USMCA, only reduce barriers among member nations. The European Union maintains external tariffs while providing production subsidies to member producers.

Production subsidies reduce firms' costs of production, shifting the supply curve rightward. This creates:

• Oversupply of products in global markets
• Depressed global prices
• Adverse impacts on non-subsidised producers outside the trading bloc
• Potential trade tensions and retaliation

Balance of payments relationships

The debt-trap cycle

A current account deficit (CAD) must be financed through the capital and financial account (KAFA) under a floating exchange rate system. This creates important linkages between international trade, investment flows, and income payments.

This flowchart demonstrates the self-reinforcing nature of external debt accumulation. Each step feeds into the next, creating a continuous cycle that can constrain economic policy choices.

Exchange rate determination

Floating exchange rate systems

Under floating exchange rates, currency values are determined by market forces of supply and demand. Multiple factors influence these forces, including:

• Relative interest rates between countries
• International competitiveness of exports
• Inflation rate differentials
• Economic growth prospects
• Speculation by foreign exchange market participants

The diagram shows the Australian dollar priced in US dollars, with equilibrium at $90$ cents. At this exchange rate, the quantity of Australian dollars demanded equals the quantity supplied, represented by $Q_e$.

Fixed exchange rate systems

Fixed exchange rate regimes require government or central bank intervention to maintain the currency at a predetermined level. The authorities must actively buy or sell currency to prevent market forces from moving the exchange rate away from the fixed level.

This diagram compares a fixed exchange rate ($80$ cents) with the market rate that would prevail under floating conditions ($75$ cents). When the fixed rate exceeds the market rate, there is excess supply of Australian dollars. The central bank must purchase the surplus currency (the distance $Q_1Q_2$) to maintain the peg, using foreign exchange reserves.

Key implications of fixed rates:

• Require substantial foreign exchange reserves
• Limit monetary policy independence
• May become unsustainable if reserves are depleted
• Can provide exchange rate stability for international trade

Impact of balance of payments components on exchange rates

All transactions recorded in the balance of payments affect currency supply and demand. Understanding these relationships is essential for predicting exchange rate movements.

An increase in demand shifts the demand curve from $D_1$ to $D_2$, appreciating the Australian dollar. This might occur due to stronger export demand or higher capital inflows attracted by rising Australian interest rates.

An increase in supply shifts the supply curve from $S_1$ to $S_2$, depreciating the Australian dollar from $80$ cents to $70$ cents. This might result from increased import demand or capital outflows as Australian investors seek opportunities abroad.

Income distribution analysis

The Lorenz curve

The Lorenz curve is a graphical tool for visualising income inequality within an economy. It plots the cumulative proportion of income received against the cumulative proportion of income recipients (households ranked from lowest to highest income).

Perfect equality would produce a $45°$ diagonal line (the "line of equality"), where each percentage of the population receives exactly that percentage of total income. In reality, income is distributed unevenly, so the actual Lorenz curve lies below this line.

The Gini coefficient

The Gini coefficient translates the Lorenz curve into a single numerical measure of inequality. It is calculated as:

$\text{Gini coefficient} = \frac{A}{A + B}$

Where:

• $A$ is the area between the Lorenz curve and the line of equality
• $B$ is the area beneath the Lorenz curve

Governments can use the Lorenz curve and Gini coefficient to:

• Monitor changes in income distribution over time
• Assess the impact of tax and transfer policies
• Compare inequality levels internationally
• Justify redistributive policies or tax reforms

Market failure and externalities

Negative externalities

Externalities occur when economic activities impose costs or benefits on third parties not involved in the transaction. The price mechanism reflects only private costs and benefits, ignoring broader social impacts. This creates market failure, where resources are allocated inefficiently from society's perspective.

The diagram shows two supply curves. The lower curve represents private costs faced by producers. The upper curve includes both private costs and external costs imposed on society. At the market equilibrium (price $P_m$, quantity $q_m$), production exceeds the socially optimal level ($q_s$). The market overproduces because producers ignore external costs they impose on others.

To achieve the socially optimal outcome, governments can:

• Impose taxes equal to the external cost (Pigouvian taxes)
• Regulate production quantities or emission levels
• Create tradable pollution permits
• Subsidise cleaner production technologies

Government policy trade-offs

The Phillips curve

Governments face difficult choices when pursuing multiple economic objectives simultaneously. The Phillips curve illustrates the short-run trade-off between inflation and unemployment.

The downward-sloping curve shows an inverse relationship: lower unemployment is associated with higher inflation, and vice versa. This trade-off arises because:

• Strong economic growth reduces unemployment but increases demand pressures
• Rising demand pulls up wages and prices, generating inflation
• Conversely, slower growth reduces inflationary pressure but increases unemployment

Minimum wages and unemployment

Another policy trade-off exists between income equality and employment. Minimum wage legislation aims to ensure fair pay and reduce income inequality, but may create unemployment if set above the market-clearing level.

When the minimum wage ($W_1$) is set above the equilibrium wage ($W_e$), the quantity of labour supplied ($L_S$) exceeds the quantity demanded ($L_D$). The gap represents unemployment: workers willing to work at the minimum wage who cannot find jobs.

The magnitude of this effect depends on:

• How far above equilibrium the minimum wage is set
• The elasticity of labour demand (how responsive employment is to wage changes)
• The flexibility of firms to adjust through productivity improvements
• Enforcement mechanisms and compliance rates

Economic growth versus environmental sustainability

Rapid economic growth may conflict with long-term environmental sustainability. If growth depletes natural resources or damages ecosystems, it can reduce the economy's productive capacity over time.

The production possibility frontier (PPF) shows the maximum combinations of goods an economy can produce with given resources and technology. Unsustainable growth practices cause the PPF to shift inward over time (from "Now" to "Future"), as environmental degradation reduces productive capacity.

Achieving sustainable growth requires:

• Investing in renewable energy and clean technologies
• Implementing environmental protection regulations
• Pricing natural resources to reflect their scarcity
• Developing circular economy approaches
• International cooperation on global environmental issues

Macroeconomic policy and the AS-AD model

The aggregate supply and aggregate demand framework

The AS-AD model provides a comprehensive framework for analysing economy-wide changes in output and price levels. It graphs the relationship between:

• General price level (vertical axis)
• Total output or real GDP (horizontal axis)

Expansionary macroeconomic policy

Expansionary policy stimulates aggregate demand through:

• Lower interest rates (expansionary monetary policy)
• Reduced taxation (expansionary fiscal policy)
• Increased government spending (expansionary fiscal policy)

The AD curve shifts rightward from $AD$ to $AD_1$. At the new equilibrium:

• Total output increases from $Y$ to $Y_1$ (higher economic growth)
• The price level rises from $P$ to $P_1$ (higher inflation)
• Unemployment falls as firms expand production

Contractionary macroeconomic policy

Contractionary policy reduces aggregate demand through:

• Higher interest rates (contractionary monetary policy)
• Increased taxation (contractionary fiscal policy)
• Reduced government spending (contractionary fiscal policy)

The AD curve shifts leftward from $AD$ to $AD_1$. At the new equilibrium:

• Total output decreases from $Y$ to $Y_1$ (lower economic growth)
• The price level falls from $P$ to $P_1$ (lower inflation)
• Unemployment rises as firms reduce production

Supply shocks and microeconomic policy

Supply-side factors can also shift the AS curve, affecting both output and prices simultaneously. Negative supply shocks (such as oil price increases or natural disasters) shift AS leftward, while positive shocks (such as technological improvements or successful microeconomic reforms) shift it rightward.

Microeconomic reforms aim to shift AS rightward by:

• Reducing production costs through deregulation
• Increasing productivity through education and training
• Enhancing competition through trade liberalisation
• Improving infrastructure to reduce business costs

Exam guidance

When interpreting diagrams:

• Identify which curves are shifting and in which direction
• Explain the economic factors causing the shifts
• Describe the impact on both price and quantity variables
• Link diagram changes to real-world economic outcomes
• Consider both short-run and long-run implications where relevant

Remember!