Income Elasticity of Demand (YED) (Cambridge International A-Level Economics)

Defining and calculating YED

• Changes in income result in changes to the demand for goods/services

  • Economists are interested in how much the quantity demanded will change for different products

• Income elasticity of demand (YED) reveals how responsive the change in quantity demanded is to a change in income

Calculation of YED

• YED can be calculated using the following formula:

$\text{YED = } \frac{\% \text{change} \text{in} \text{quantity} demanded}{\% \text{change} \text{in} income} = \frac{\% \Delta \text{in} QD}{\% \Delta \text{in} \mathrm{Y} }$

Worked Example A consumer's income rises from £100 to £125 a week. They originally consumed 12 bagels at the local bakery, but this increased to 15 bagels a week.

Calculate the YED of the bagels

Step 1: Calculate the % change in QD

****$% \Delta \text{QD} = \frac{15 - 12}{12} \times 100

% \Delta \text{QD} = + 25 %$****

Step 2: Calculate the % change in Y

$% \Delta Y = \frac{125 - 100}{100} \mathrm{x} 100

% \Delta Y = + 25 %$

Step 3: Insert the above values in the YED formula

$\text{PED} = \frac{% \Delta \text{in} QD}{% \Delta \text{in} \mathrm{Y} }

Y \text{ED} = \frac{25}{25}

Y \text{ED} = + 1 $

Even when the YED value is positive, the answer must clearly state this

Interpreting YED values

• The YED value can be positive or negative and the value is important in determining the type of good

  • A good with a positive YED value is considered to be a normal good

    • Normal goods can be classified as necessities or luxuries

  • A good with a negative YED value is considered to be an inferior good

The meaning of YED values

Factors affecting YED

• YED is influenced by any factors in an economy which change the wages of workers

  • During a recession wages usually fall and demand for inferior goods rises while demand for luxury goods falls
  • During a period of economic growth and rising wages, demand for luxury goods increases while demand for inferior goods decreases
  • Other influences on income include minimum wage legislation, taxation, increased international trade

Normal goods

• These are items people tend to buy more of as their income rises. For example, as household earnings grow, purchases of fresh produce or home appliances may increase
• Normal goods have a positive YED, indicating a rise in demand when income increases or vice versa

Inferior goods

• Demand for these products tends to fall when income goes up, as consumers switch to higher-quality alternatives

  • For instance, instant noodles or budget laundry detergent might be replaced by premium brands.

• Inferior goods have a negative YED, and the size of the value reflects how strongly demand reacts to income changes

Necessities

• These are essential items that people continue to buy despite income changes

  • Examples include staple foods like bread or cooking oil

• They are normal goods, as their YED is positive but close to zero, showing that demand responds by a smaller percentage than the percentage change in income

Luxury or superior goods

• These normal goods see a significantly greater percentage rise in demand as income increases

  • Designer handbags, high-end electronics, or gourmet dining experiences fall into this category

• They have a YED greater than 1, meaning demand is highly responsive to income growth

Exam Hint You should consider that the classification of a good can vary depending on the consumer’s income. For example, public transport might be a necessity for lower-income households but considered an inferior option by wealthier individuals who prefer private vehicles

Implications for decision-making of YED For firms

Implications for decision-making of YED

• YED is crucial for firms as it helps them understand consumer behaviour, analyse markets, plan strategies, make informed investment decisions, and adapt to changes in the sectoral structure of the economy
• By assessing the income elasticity of demand, firms can effectively navigate evolving market dynamics and position themselves for sustainable growth
• In developing countries such as India, China, Malaysia, and Pakistan, rising incomes often lead to increased demand for personal vehicles. As people upgrade from basic models to premium brands, manufacturers respond by expanding production facilities

For firms

• Products with high positive YED are luxury goods

  • Demand rises more than proportionately as incomes increase
  • Firms may target high-income consumers during periods of economic growth

• Products with low positive YED are normal necessities

  • Demand rises slowly as income increases
  • Firms may expect stable sales even if incomes rise

• Products with negative YED are inferior goods

  • Demand falls as incomes increase
  • Firms may face declining sales as living standards improve

For governments

• YED helps predict how demand for goods and services changes during economic growth or recession
• Goods with high YED may experience large fluctuations in demand over the business cycle
• Demand for necessities with low YED is more stable, which is important for planning public services

For the economy

• High YED products contribute more to economic growth during expansions
• Industries producing inferior goods may decline as incomes rise