Income Effect, Substitution Effect, and Price Effect (Indifference Curve Analysis) (Graphical Explanation for Competitive Exams – Home Academy)

 

Income Effect, Substitution Effect, and Price Effect (Indifference Curve Analysis)

(Graphical Explanation for Competitive Exams – Home Academy)

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1. Price Effect Diagram

The Price Effect shows how a change in the price of a good affects the quantity demanded.
It is the combined effect of Income Effect and Substitution Effect.

Diagram: Price Effect

Good Y
  |
  |            IC2
  |           *
  |         *
  |       *
  |     *      IC1
  |   *
  | *
  |____________________________
        BL1      BL2
           Good X

Explanation

BL1 → Initial Budget Line

BL2 → New Budget Line after price fall
IC1 → Initial satisfaction
IC2 → Higher satisfaction

When the price of Good X falls, the budget line rotates outward and the consumer moves to a higher indifference curve.

Price Effect = Substitution Effect + Income Effect

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2. Substitution Effect Diagram

The Substitution Effect occurs when a consumer substitutes a cheaper good for a relatively expensive good.

Diagram: Substitution Effect

Good Y
  |
  |           IC1
  |          *
  |        *
  |      *
  |    *
  |  *
  | *
  |__________________________
        A      B
           Good X

Explanation

Movement from Point A to Point B

Due to relative price change
Consumer substitutes cheaper good for expensive good

Substitution effect always works in the opposite direction of price change.

Example
If the price of tea falls, the consumer buys more tea instead of coffee.

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3. Income Effect Diagram

The Income Effect shows the change in consumption due to a change in real income caused by price change.

Diagram: Income Effect

Good Y
  |
  |             IC3
  |           *
  |        *
  |      *
  |    *
  |  *
  | *
  |__________________________
        A   B   C
           Good X

Explanation

A → Initial equilibrium

B → After substitution effect
C → Final equilibrium after income effect

If price falls, real income increases, so the consumer moves to a higher indifference curve.

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4. Difference Between Income Effect and Substitution Effect

Basis	Substitution Effect	Income Effect
Meaning	Change due to relative price change	Change due to change in purchasing power
Cause	Price change	Real income change
Direction	Always opposite to price change	Can be positive or negative
Goods affected	All goods	Normal and inferior goods

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5. Example to Understand

Suppose:

Price of Rice decreases

1️⃣ Substitution Effect
Consumer buys more rice instead of wheat.

2️⃣ Income Effect
Consumer feels richer and buys more food.

3️⃣ Total Price Effect
Demand for rice increases.

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Important Points for Competitive Exams

Most frequently asked questions come from:

Price Effect = Income Effect + Substitution Effect

Substitution Effect always negative
Income effect positive for normal goods
Indifference curve analysis developed by
John Hicks

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MCQ Questions

1 Price Effect is equal to

A Income Effect – Substitution Effect
B Income Effect + Substitution Effect
C Income Effect × Substitution Effect
D None

✅ Answer: B Income Effect + Substitution Effect

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2 Substitution Effect occurs due to

A Income change
B Price change
C Population change
D Tax change

✅ Answer: B Price change

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3 Income Effect occurs because of

A Change in real income
B Change in population
C Change in production
D Change in demand

✅ Answer: A Change in real income

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4 Substitution Effect always

A Positive
B Negative
C Constant
D Zero

✅ Answer: B Negative

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5 Indifference curve analysis was given by

A John Hicks
B Adam Smith
C Keynes
D Ricardo

✅ Answer: A John Hicks

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