Aggregate Demand: AD Curve, Effective Demand & Business Policy

TAKEAWAYS:

• AD = C + I + G + (X–M): Aggregate demand is the sum of consumption, investment, government spending, and net exports, sloping downward due to the real-balance effect, interest-rate effect, and foreign-trade effect.
• Effective demand ≠ full-employment output: Keynes argued that an economy can operate below capacity (e.g., Nepal’s 2020 GDP drop to 1.9% growth) because aggregate supply is horizontal at low output levels.
• AD shifts vs. movements: A shift (right/left) occurs from changes in C, I, G, or X–M; a movement along the curve happens when P changes.
• Business applications: Firms like Daraz use AD analysis to predict demand surges (e.g., Dashain sales) and adjust inventory, while NEPSE tracks investor sentiment via stock demand curves.
• Policy tools: Governments use fiscal policy (G/T changes) and monetary policy (i changes) to shift AD and hit targets like Nepal’s inflation control (6.5% in 2023) or GDP growth (4.5% in 2024).
• Real-world trap: Classical economists assumed Say’s Law ("supply creates demand"), but the 2008 global financial crisis proved effective demand matters—central banks worldwide used AD stimulus to recover.

1. What is Aggregate Demand (AD)?

Aggregate demand (AD) is the total demand for final goods and services in an economy at a given price level, measured as real GDP (Y). It combines:

• Consumption (C): Household spending on goods/services.
• Investment (I): Business spending on capital (machinery, buildings).
• Government spending (G): Public expenditure (roads, schools).
• Net exports (X–M): Exports minus imports.

Why does AD slope downward? Three key effects explain the inverse relationship between price level (P) and real GDP (Y):

2. The AD Equation and Worked Example

The AD curve can be expressed as: $$AD=C+I+G+(X-M)$$ Where:

• C = 300 + 0.75(Y–T): Consumption depends on disposable income (Y–T).
• I = 600 – 6000i: Investment falls as interest rates (i) rise.
• G = 300: Fixed government spending.
• X–M: Net exports (assume X–M = 0 for simplicity).

Worked Example: Nepal’s AD in 2023 Assume:

• T = 240 + 0.2Y (taxes rise with income).
• i = 5% (central bank rate).
• Ms = 600 (money supply), M_tp = 300 – 9000i (money demand).

Step 1: Find equilibrium income (Y) and interest rate (i) From the money market: Ms = M_tp \implies 600 = 300 - 9000i \implies i = 0.033 \text{ (3.3%)} From the goods market (AD = AS at equilibrium): $$Y=C+I+G=[300+0.75(Y-240-0.2Y)]+[600-6000(0.033)]+300$$ Simplify: $$Y=300+0.75(0.8Y-240)+600-200+300$$ $$Y=1000+0.6Y-180⟹0.4Y=820⟹Y=2050\text{ (in billions NPR)}$$ Interpretation: Nepal’s equilibrium GDP is 2050 billion NPR, below potential output (say, 2500 billion). This gap signals unemployment or underutilized capacity.

3. Effective Demand vs. Classical Theory

Why Effective Demand Matters for Businesses

• Daraz’s Dashain Sales: AD spikes due to C ↑ (consumers stock up). Daraz adjusts inventory using AD forecasts.
• NEPSE Stock Market: AD for shares depends on investor confidence (I). A rightward AD shift raises stock prices.
• Pathao Drivers: AD for rides depends on G (government subsidies) and X–M (tourist demand).

4. Shifts in AD: Causes and Effects

AD shifts occur when C, I, G, or X–M change at every price level. Use this table to memorize:

5. AD and Business Strategy

Case Study: Daraz’s AD-Driven Pricing Daraz uses AD analysis to:

1. Predict demand surges: Dashain/Teej sales → C ↑ → AD shifts right.
2. Adjust inventory: Avoid overstocking (↓AD risk) or shortages (↑AD risk).
3. Dynamic pricing: Lower prices during recessionary gaps (↓AD) to boost sales.

Graph: Daraz’s AD During Dashain

graph TD
    A["AD Before Dashain"] -->|"Prices stable"| B["Normal AD Curve"]
    B --> C["Dashain: C ↑"]
    C --> D["AD Shifts Right"]
    D --> E["Daraz: ↑Inventory, ↑Prices"]
    E --> F["Post-Dashain: AD Returns to Normal"]

NEPSE Example: AD and Stock Prices

• 2022: AD for shares fell due to global recession (↓I) → NEPSE index dropped.
• 2023: AD rose due to remittance-driven C ↑ → NEPSE recovered.

6. AD and Macroeconomic Policy

Governments use fiscal and monetary policy to shift AD and achieve goals like:

• Full employment (Y = potential output).
• Price stability (inflation target: 6.5% in Nepal).
• Economic growth (4.5% target for 2024).

7. AD and Inflation: Demand-Pull Inflation

When AD grows faster than AS, prices rise (demand-pull inflation). Example: Nepal 2022

• Cause: Post-COVID recovery → C ↑, I ↑, G ↑ → AD shifted right.
• Effect: Inflation hit 8.2% (above target).
• Policy Response:
  • Monetary: NBR raised interest rates to ↓I and C.
  • Fiscal: Government controlled G to avoid overheating.

Graph: Demand-Pull Inflation

In the Real World

1. Khalti and eSewa: These apps rely on AD for digital payments. When C ↑ (e.g., during Dashain), transaction volumes spike. Khalti uses AD data to predict cash flow needs and adjust liquidity.
2. Daraz’s Order Fulfillment: AD determines warehouse stock. During monsoon season, AD for umbrellas and raincoats shifts right. Daraz pre-orders inventory based on historical AD patterns.
3. NTC’s Tariff Adjustments: When I ↑ (e.g., businesses expanding), NTC monitors AD for electricity. If demand outpaces supply, tariffs rise to ↓AD temporarily and signal investment in new power plants.

Exam Tip

1. Diagrams are 50% of marks: Always draw AD curves for shifts/movements. Label:
   • Axes: P (price level) vs. Y (real GDP).
   • Shifts: C, I, G, X–M with arrows.
   • Movements: P changes (dashed lines for effects).
2. Link to Nepal: Use NEPSE, Daraz, or NBR policies in answers. Example:

   "Like Daraz adjusting inventory during Dashain, the Nepal Rastra Bank uses expansionary monetary policy to shift AD right when remittance-driven consumption falls."

3. Effective demand vs. classical: Compare horizontal AS (Keynes) vs. vertical AS (Classical). Mention sticky wages and 2008 crisis as proof.
4. Policy mix: Questions often ask how fiscal + monetary policy work together. Example:

   "To reduce unemployment in Nepal (2020), the government could ↑G (fiscal) while the NBR could ↓i (monetary) to shift AD right."

5. Avoid common mistakes:
   • ❌ Saying "AD shifts when P changes" (wrong: that’s a movement).
   • ❌ Ignoring net exports (X–M) in AD equations.
   • ❌ Forgetting assumptions (e.g., fixed G, no crowding out).

Final Worked Example for Exam Practice Question: "Explain how a depreciation of the Nepali rupee affects AD. Use a diagram and a real-world example." Answer:

1. Effect on AD:
   • Depreciation makes exports (X) cheaper and imports (M) expensive → X–M ↑.
   • This shifts AD right at every price level.
2. Diagram:

3. Real-World Example:
   • 2023 NPR Depreciation: NPR fell from 130 to 150 per USD.
   • Result: AD shifted right due to ↑X (hydropower, textiles) and ↓M (fewer imports).
   • Impact: GDP growth rose to 4.5% (2024 target) as net exports contributed 12% to AD.

Key Formula to Memorize: $$AD=C(Y-T)+I(i)+G+(X(e,P)-M(e,P))$$ Where:

• e = exchange rate,
• P = price level,
• i = interest rate.