What is Elasticity in UPPSC PCS?

Elasticity is a topic in the Economics syllabus of UPPSC PCS. It carries a weight of 3% in the exam. Our notes cover the key concepts, formulas, and problem-solving approaches you need to master this topic.

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Elasticity of Demand

What is Elasticity?

Elasticity of Demand measures how responsive the quantity demanded of a good is to changes in its price, income, or other factors.

Price Elasticity of Demand (PED) = % Change in Quantity Demanded / % Change in Price

Types of Elasticity

1. Price Elasticity of Demand (PED)

Type	Value	Meaning
Perfectly Elastic	E = ∞	Tiny price change → huge demand change
Highly Elastic	E > 1	Demand changes more than price
Unit Elastic	E = 1	Demand changes exactly as price does
Inelastic	E < 1	Demand changes less than price
Perfectly Inelastic	E = 0	Price change → no demand change

2. Income Elasticity of Demand (YED)

Normal Goods: YED > 0 (as income rises, demand rises)
Inferior Goods: YED < 0 (as income rises, demand falls)

3. Cross Elasticity of Demand (XED)

Measures how demand for good A changes when price of related good B changes.

Substitutes: XED > 0 (tea vs coffee)
Complements: XED < 0 (pen vs ink)

Factors Affecting PED

Availability of substitutes — More substitutes → More elastic
Necessity vs Luxury — Necessities are inelastic
Proportion of income spent — Larger share → More elastic
Time period — Long run → More elastic (more adjustment possible)
Habit — Addictive goods → Inelastic

Methods to Calculate PED

Percentage Method

PED = (Change in Qty / Original Qty) × 100
      ─────────────────────────────────
      (Change in Price / Original Price) × 100

Point Method (for specific points on demand curve)

PED = (dq/dP) × (P/Q)

Total Expenditure Method

Elastic (E > 1): Price ↓ → Total Expenditure ↑
Unit Elastic (E = 1): Total Expenditure constant
Inelastic (E < 1): Price ↓ → Total Expenditure ↓

Practical Applications

Taxation Policy: Inelastic goods (alcohol, tobacco) → higher taxes yield more revenue
Price Discrimination: Different elasticity → different pricing
Farmer’s Problem: Agricultural demand is inelastic → price swings heavily with supply changes
Minimum Support Prices: Government buys when prices fall below cost

UPPSC PCS Specific Points

⚡ Exam Tip: Questions on elasticity are frequently asked in UPPSC PCS. Focus on:

Numerical problems on PED calculation
Graphs showing elastic/inelastic demand curves
Relationship between PED and Total Revenue

High-yield: The “total expenditure method” is a quick way to determine elasticity without calculating ratios — frequently tested in prelims.

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