Aggregate Demand and Supply

Quick Answer:
Aggregate Demand (AD) and Aggregate Supply (AS) in CAPE Economics Unit 2 cover the foundations of macroeconomic analysis. You’ll need to understand the components of AD, the determinants of AS, how equilibrium is established, and the effects of government policy, inflation, unemployment, and growth within the AD–AS framework.

📘 Aggregate Demand (AD)

  • Definition: Total planned expenditure on goods and services in an economy at a given price level.

  • Equation:
    [ AD = C + I + G + (X - M) ]

    • C (Consumption): Household spending, influenced by income, interest rates, wealth, and expectations.

    • I (Investment): Business spending on capital, affected by interest rates, confidence, and technology.

    • G (Government Spending): Expenditure on goods, services, and infrastructure.

    • X – M (Net Exports): Exports minus imports, influenced by exchange rates, global demand, and competitiveness.

  • Determinants of AD:

    • Fiscal policy (taxes, spending)

    • Monetary policy (interest rates, money supply)

    • External factors (exchange rates, global trade conditions)

  • AD Curve:

    • Downward sloping due to wealth effect, interest rate effect, and net export effect.

    • Shifts occur when any component of AD changes (e.g., increase in G shifts AD outward).

📗 Aggregate Supply (AS)

  • Definition: Total output producers are willing and able to supply at a given price level.

  • Short-Run AS (SRAS):

    • Upward sloping because wages and some input costs are sticky.

    • Influenced by production costs, wages, taxes, and supply shocks.

  • Long-Run AS (LRAS):

    • Vertical at full employment output (potential GDP).

    • Determined by factors of production: land, labor, capital, and technology.

    • Shifts occur with changes in productivity, labor force, or capital stock.

📊 AD–AS Equilibrium

  • Short-Run Equilibrium: Intersection of AD and SRAS determines output and price level.

  • Long-Run Equilibrium: Economy tends toward LRAS; output is fixed at full employment, prices adjust.

  • Inflationary Gap: AD exceeds full employment output → upward pressure on prices.

  • Deflationary Gap: AD below full employment output → unemployment and idle resources.

📉 Policy Implications

  • Fiscal Policy:

    • Expansionary (↑G, ↓Taxes) shifts AD outward.

    • Contractionary (↓G, ↑Taxes) shifts AD inward.

  • Monetary Policy:

    • Expansionary (↓Interest rates, ↑Money supply) boosts C and I.

    • Contractionary (↑Interest rates, ↓Money supply) reduces C and I.

  • Supply-Side Policies:

    • Aim to shift LRAS outward by improving productivity, education, infrastructure, and technology.

🌍 Open Economy Considerations (important for CAPE)

  • Exchange rates affect net exports.

  • Trade openness means external shocks (oil prices, global recessions) strongly influence AD and AS.

  • Balance of payments and capital flows interact with AD–AS outcomes.

📝 Exam Tips for CAPE Unit 2

  • Know diagrams: AD curve, SRAS curve, LRAS curve, equilibrium shifts.

  • Be able to explain gaps: Inflationary vs deflationary.

  • Apply to Caribbean context: Small open economies, reliance on imports/exports, tourism, remittances.

  • Link policies to outcomes: Fiscal and monetary policy effectiveness in open economies.

In summary:
Aggregate Demand focuses on spending (C, I, G, X–M), Aggregate Supply focuses on production capacity, and their interaction determines output, employment, and price levels. CAPE Unit 2 emphasizes both short-run fluctuations and long-run growth, with strong attention to policy and open-economy dynamics.

Would you like me to create a visual study guide (diagrams + summary tables) for AD–AS so you can revise faster?