Income, Employment & Keynesian Theory: Circular Flow, AD-AS, Multiplier

TAKEAWAYS:

• Circular flow shows how money moves between households and firms, creating income and spending.
• Aggregate demand (AD) is total spending by households, firms, government, and foreign buyers.
• Aggregate supply (AS) is total output firms produce at different price levels—short-run vs. long-run curves differ.
• Equilibrium income is where AD = AS; shifts in AD cause changes in employment and output.
• Multiplier effect explains how an initial spending boost creates more income through repeated spending cycles.
• Unemployment types (frictional, structural, cyclical) arise when AD is too low for full employment.

1. Circular Flow of Income

The economy is like a circular system where money and goods/services keep moving between households and firms.

flowchart TD
    A["Households"] -->|"Factors of Production (Land, Labour, Capital, Entrepreneurship)"| B["Firms"]
    B -->|"Goods & Services"| A
    A -->|"Consumption Expenditure (C)"| B
    B -->|"Wages, Rent, Interest, Profit"| A
    C["Government"] -->|"Taxes"| A
    C -->|"Government Spending (G)"| B
    D["Foreign Sector"] -->|"Exports (X)"| B
    D -->|"Imports (M)"| A

Key Points:

• Households supply factors of production (land, labour, capital, entrepreneurship) to firms.
• Firms pay income (wages, rent, interest, profit) to households.
• Households spend on goods/services (consumption, C).
• Government collects taxes (T) and spends (G).
• Foreign sector buys exports (X) and sells imports (M).

Why is this important?

• Shows how income is earned and spent, keeping the economy running.
• If spending (AD) falls, firms produce less → unemployment rises.

Households, firms, government, and foreign sector interactions (Image: Ari89, CC0, via Wikimedia Commons)

2. Aggregate Demand (AD) and Its Components

AD = Total demand for goods/services in an economy at different price levels. It is made up of:

1. Consumption (C) – Spending by households.
2. Investment (I) – Spending by firms on machinery, buildings, etc.
3. Government Spending (G) – Roads, schools, hospitals.
4. Net Exports (X – M) – Exports minus imports.

AD Curve Shape:

• Downward-sloping because:
  • Wealth effect: Lower prices → people feel richer → spend more.
  • Interest rate effect: Lower prices → banks lend more → investment rises.
  • Exchange rate effect: Lower domestic prices → exports rise, imports fall.

Graph of AD:

graph LR
    A["Price Level (P)"] -->|"↓"| B["AD"]
    B -->|"↑"| C["Real GDP (Y)"]

Example: If the price level falls from 120 to 100, AD increases from ₹500 crore to ₹600 crore (due to higher consumption and investment).

3. Aggregate Supply (AS) – Short-Run vs. Long-Run

AS = Total output firms are willing to produce at different price levels.

Short-Run AS (SRAS)

• Upward-sloping because:
  • Firms increase production if prices rise (higher profits).
  • Fixed factors (like machinery) cannot be changed immediately.
• Assumption: Some resources are unused (unemployment exists).

Long-Run AS (LRAS)

• Vertical at full employment (Yf) because:
  • All resources are fully employed.
  • No unused capacity—economy operates at potential GDP.
  • Price changes do not affect output in the long run.

Graph of AS:

graph LR
    A["Price Level (P)"] -->|"↑"| B["SRAS"]
    B -->|"↑"| C["Real GDP (Y)"]
    D["LRAS"] -->|"Vertical"| E["Full Employment (Yf)"]

Why the difference?

• Short-run: Firms can hire more workers, use idle machines.
• Long-run: Economy hits its maximum capacity—no more growth possible without new technology or resources.

4. Equilibrium Income (AD = AS)

Equilibrium occurs where AD = AS.

• At this point:
  • Planned spending = Actual output.
  • No unsold goods (inventories stable).
  • Full employment (if at LRAS).

Graph of Equilibrium:

graph LR
    A["AD"] -->|"Intersects"| B["SRAS"]
    B -->|"Equilibrium"| C["Y* (Equilibrium Output)"]
    D["LRAS"] -->|"Vertical"| C

Example: If AD = ₹1000 crore and AS = ₹1000 crore, the economy is in equilibrium at Y = ₹1000 crore.

What if AD shifts?

Why does this matter?

• If AD is too low, firms produce less → unemployment rises (recession).
• If AD is too high, prices rise → inflation.

5. The Multiplier Effect

When government or firms spend more, income increases more than the initial spending due to the multiplier effect.

How it works:

1. Initial spending (ΔI or ΔG) → Firms produce more → Income rises by ΔI.
2. Households spend part of new income (MPC) → Firms get more orders → Income rises again.
3. This keeps happening until total income increase = Initial spending × Multiplier (k).

Formula: $$\text{Multiplier (k)}=\frac{1}{1-\text{MPC}}\text{or}\frac{\Delta Y}{\Delta I}=k$$ Where:

• MPC (Marginal Propensity to Consume) = Fraction of extra income spent.
• MPS (Marginal Propensity to Save) = Fraction of extra income saved.

Example: If MPC = 0.8, then: $$k=\frac{1}{1-0.8}=5$$

• If government spends ₹100 crore, total income rises by: $$\Delta Y=k\times \Delta I=5\times 100=₹500\text{ crore}$$

Why is this useful?

• Shows how small changes in investment or government spending can boost the economy.
• Helps explain why recessions are deep (small spending cuts → big income drops).

6. Types of Unemployment (Why AD Matters)

When AD is too low, firms cut production → unemployment rises.

How AD affects unemployment:

• If AD falls, firms reduce hiring → cyclical unemployment rises.
• If AD rises, firms hire more → unemployment falls.

7. Policy Implications (Fiscal Policy)

Governments can shift AD to fix unemployment or inflation.

Example (Nepal):

• 2020 Lockdown: AD fell → unemployment rose → government gave cash aid to poor families (↑C) to boost AD.

Exam Tip: How to Score Full Marks

✅ Understand AD-AS shifts – Always ask:

• Who is spending more/less?
• Is it short-run or long-run?
• Does it affect output or just prices?

✅ Multiplier questions – Remember:

• k = 1 / (1 – MPC)
• Always show calculations (NEB loves step-by-step).

✅ Unemployment types – Link them to AD:

• Cyclical unemployment = Low AD problem.

✅ Real-world examples – Nepal’s economy:

• Remittances (X) boost AD.
• Droughts reduce agricultural output (AS shift left).

✅ Diagrams are key! – Always draw:

• AD-AS equilibrium (label shifts).
• Circular flow (for income explanation).
• Multiplier effect (show repeated spending rounds).

NEB Board-Style Questions (Practice)

Short Answer (5 marks)

1. "Explain the components of Aggregate Demand with an example from Nepal’s economy." Answer:

   • C (Consumption): Nepali families spending on food, clothes.
   • I (Investment): A factory buying new machines.
   • G (Government): Building a new hospital in Kathmandu.
   • X – M (Net Exports): Selling jute to India (X) vs. buying petroleum (M).

2. "Why is the Short-Run AS curve upward-sloping?" Answer:

   • Firms can hire more workers or use idle machinery.
   • Higher prices → higher profits → more production.
   • But in the long run, all resources are fully used → LRAS is vertical.

Long Answer (10 marks)

3. "Using AD-AS diagram, explain how an increase in government spending affects equilibrium income and employment. What happens if this spending leads to inflation?" Answer:

   • Step 1: Draw initial AD and AS, mark equilibrium at Y1, P1.
   • Step 2: Government spends more (G ↑) → AD shifts right to AD’.
   • Step 3: New equilibrium at Y2 > Y1 (↑output), P2 > P1 (↑prices).
   • Step 4: If Y2 = Full Employment (Yf), further AD increase causes only price rise (inflation).

4. "Calculate the multiplier effect if MPC = 0.75 and initial investment increases by ₹200 crore." Answer:

   • MPC = 0.75 → MPS = 1 – 0.75 = 0.25
   • k = 1 / (1 – 0.75) = 4
   • Total income increase = 4 × ₹200 crore = ₹800 crore

Common Mistakes to Avoid

❌ Forgetting to label axes in AD-AS diagrams (NEB deducts marks!). ❌ Mixing short-run and long-run AS – Always specify which one you’re using. ❌ Ignoring real-world examples – Nepal’s remittances, droughts, or government policies are highly scored. ❌ Wrong multiplier formula – Always use k = 1 / (1 – MPC).

Final Tip:

• AD shifts = Spending changes (C, I, G, X-M).
• AS shifts = Supply shocks (droughts, oil price changes).
• Multiplier = How spending ripples through the economy.

Good luck! 🚀 Study these diagrams and examples well—they appear every year in NEB exams.