Factors influencing price elasticity of demand

Price elasticity of demand (PED) measures how much the quantity demanded of a good changes in response to a change in its price. Several factors affect whether demand is elastic (responsive to price changes) or inelastic (less responsive).

Key factors that influence PED

• Availability of substitutes - Goods with many close substitutes have more elastic demand because consumers can easily switch if prices rise. Broader categories have fewer substitutes and more inelastic demand.
• Type of good or service - Essential items have inelastic demand as consumers need them regardless of price. Non-essentials have elastic demand. Habit-forming goods and urgent purchases are inelastic, while versatile products also tend to be inelastic.
• Percentage of income spent on the good - Expensive items that take up a large share of income have elastic demand as buyers shop around. Cheap items have inelastic demand since price changes barely affect budgets.
• Time period - Demand is more inelastic in the short run when alternatives are hard to find, but becomes more elastic in the long run as consumers adjust habits, loyalties, and search for options.

Relationship between total revenue and price elasticity of demand

Total revenue is the money a firm earns from sales, calculated as price per unit multiplied by quantity sold. The PED of a product influences how changes in price affect this revenue.

How PED changes along a demand curve

PED varies on a straight-line demand curve. At high prices and low quantities, PED is highly elastic. At the midpoint, PED equals -1 (unit elastic). At low prices and high quantities, PED approaches zero (inelastic).

Total revenue reaches its maximum when PED is -1, so firms aim to price near the demand curve's midpoint for highest revenue.

Effects of price changes on total revenue

• For elastic demand (PED < -1) - Lowering price increases total revenue. Raising price decreases total revenue.
• For inelastic demand (-1 < PED < 0) - Lowering price decreases total revenue. Raising price increases total revenue.
• For unit elastic demand (PED = -1) - Price changes do not affect total revenue.

Income elasticity of demand for normal and inferior goods

Income elasticity of demand (YED) measures how the quantity demanded of a good changes in response to a change in consumer income. It helps classify goods based on demand patterns.

Normal goods

Normal goods have a positive YED (greater than 0 but less than 1), meaning demand rises as income increases. If YED is greater than 1, the good is a luxury or superior good. These are the most common goods.

Inferior goods

Inferior goods have a negative YED (less than 0), so demand falls as income rises. Consumers switch to higher-quality alternatives when incomes increase.

Cross elasticity of demand for substitutes, complements, and independent goods

Cross elasticity of demand (XED) measures how the quantity demanded of one good changes in response to a price change in another good. It reveals relationships between products.

Substitutes

• Substitutes have positive XED values.
• A price fall in one reduces demand for the other.
• Closer substitutes have higher positive XEDs.

Complements

• Complements have negative XED values.
• A price rise in one reduces demand for the other.

Independent goods

• Independent goods have an XED of zero.
• Price changes in one do not affect demand for the other.

Practical uses of elasticities of demand for firms and governments

Elasticities help organisations predict and respond to market changes, supporting strategic decisions in business and policy.

Uses for firms

• Sales forecasting - Knowing a product's YED and expected income changes allows prediction of future sales volumes.
• Pricing policy - For normal goods during income falls, price reductions can help limit demand drops.
• Supply strategy - Firms may produce a mix of goods with different YEDs to stabilise revenue across economic cycles.
• Competitive response - Understanding XED helps firms react to rivals' price changes.

Uses for governments

• Policy planning - Elasticities inform how demand for services shifts during economic changes, aiding resource allocation.
• Recession management - In downturns, falling incomes may boost demand for public services like transport, requiring increased provision.