The definition and components of aggregate demand

Aggregate demand (AD) represents the total planned spending on domestic goods and services at different average price levels per period of time. It differs from gross domestic product (GDP), which measures actual output produced as a specific figure, while AD indicates planned spending as a function across various price levels.

Formula for aggregate demand

$AD=C+I+G+(X-M)$

Where:

• C = Consumption expenditures by households
• I = Investment expenditures by businesses
• G = Government expenditures
• X - M = Net exports (exports minus imports)

Characteristics of the aggregate demand curve

The aggregate demand curve illustrates the relationship between the average price level and the total quantity of goods and services demanded in an economy. It is plotted with real output on the horizontal axis and the average price level (APL) on the vertical axis.

The curve slopes downwards, showing that as the average price level rises, the quantity of real output demanded decreases, and vice versa.

Factors causing the negative slope of the aggregate demand curve

The downward slope of the AD curve arises from three main effects that reduce planned spending as prices increase.

The wealth effect

Higher prices reduce the real value of money and assets held by households, leading to decreased consumption spending.

The trade effect

Higher domestic prices make exports less competitive in international markets while making imports more attractive, resulting in a decline in net exports.

The interest rate effect

Higher prices increase the demand for money, which raises interest rates and discourages consumption and investment spending.

Determinants of each component of aggregate demand

Various factors influence the levels of consumption, investment, government spending, and net exports, affecting the overall position of the AD curve.

Consumption expenditures (C)

Consumption refers to household spending on goods and services.

Determinants of consumption expenditures:

• Interest rates - Higher rates increase the cost of borrowing, reducing spending on consumer durables such as refrigerators and furniture.
• Consumer confidence - Greater optimism about the economy encourages spending on major purchases.
• Household wealth - Increases in the value of investment portfolios or real estate boost spending power.
• Personal income taxes - Lower taxes raise disposable income, leading to higher consumption.
• Household indebtedness - High levels of credit card or loan balances limit current spending.
• Price level expectations - Expectations of future inflation prompt households to accelerate purchases now.

Investment expenditures (I)

Investment involves business spending on capital goods and infrastructure.

Determinants of investment expenditures:

• Interest rates - Higher rates reduce the profitability of projects, such as purchasing manufacturing equipment.
• Business confidence - Optimism about future sales encourages expansion, like building new factories.
• Technology - Rapid innovations in an industry drive increased capital spending.
• Business taxes - Lower corporate taxes improve after-tax returns on investment projects.
• Corporate indebtedness - High existing debt discourages additional borrowing for new capital.
• Keynes' "animal spirits" - Entrepreneurial decisions often follow herd behaviour, influencing investment trends.

Government expenditures (G)

Categories of government expenditures:

• Current spending on goods and services, such as salaries for public sector workers.
• Capital spending on infrastructure, like roads and schools.
• Transfer payments, which redistribute income but are not included in national income calculations.

Purposes of government expenditures:

• Providing public and merit goods, such as defence and education.
• Regulating markets to ensure fair competition.
• Redistributing income to reduce inequality.
• Influencing aggregate demand through fiscal policy, such as increasing spending during economic downturns.

Net exports (X - M)

Net exports represent the difference between exports and imports.

Determinants of net exports:

• Trading partners' income - Economic growth in other countries increases demand for domestic exports.
• Exchange rates - Depreciation of the domestic currency makes exports cheaper and more competitive abroad.
• Trade policies - Imposing tariffs on foreign goods, such as electronics, encourages domestic purchases and reduces imports.

Shifts in aggregate demand

Shifts in the AD curve occur when there are changes in the determinants of its components, leading to a new level of planned spending at every price level. These shifts do not result from changes in the average price level itself.