TutorChase logo
IB DP Economics Study Notes

2.5.2 Income Elasticity of Demand (YED)

Income Elasticity of Demand (YED) is a vital concept in economics, offering a lens through which we can understand how changes in income levels impact the demand for various goods and services. By analysing YED, businesses and policymakers can make informed decisions about production, pricing, and policy. Understanding the Income Elasticity of Demand complements the knowledge on non-price determinants of demand, providing a more comprehensive view of market dynamics.


Income Elasticity of Demand (YED) gauges the responsiveness of the quantity demanded of a particular good or service in relation to a change in consumers' income. It's a measure that provides insights into the nature of goods and how they might be influenced by shifts in economic prosperity or downturns.

Mathematically, YED is expressed as:

YED= Percentage change in quantity demanded / Percentage change in income​


Calculating YED is straightforward once you have the necessary data. The formula is:

YED=(Change in quantity demanded / Average quantity demanded) / (Change in income / Average income​)


Imagine a scenario where the average income of consumers in a region increases by 15%. Subsequently, the demand for high-end home theatre systems, considered a luxury, rises by 30%. To find the YED:

YED=30% / 15% = 2​

This result indicates that for every 1% increase in income, the demand for the home theatre systems in question rises by 2%. This concept is closely related to understanding the Price Elasticity of Demand (PED), as both elasticity measures are crucial for effective pricing strategies.


The value of YED can be positive, negative, or zero. The nature of the good in question largely determines this. Here's a deeper dive into the determinants:

1. Nature of the Good

  • Normal Goods: These are items for which demand rises as income increases. They possess a positive YED.
    • Necessities: Within the realm of normal goods, necessities have a YED between 0 and 1. This suggests that even if income rises, the demand for these goods increases, but not as much proportionally. Essential household items, basic clothing, and staple foods fall into this category.
    • Luxuries: These goods have a YED greater than 1, indicating that their demand is highly sensitive to income fluctuations. Designer clothing, luxury vehicles, and high-end electronics are examples. The demand for luxuries versus necessities further illustrates the impact of taxation on consumer choices and spending.
Graph of income elasticity of demand for normal goods and luxury goods

A graph illustrating income elasticity of demand for normal goods and luxury goods.

Image courtesy of thetutoracademy

  • Inferior Goods: These are products for which demand diminishes as income grows. They are characterised by a negative YED. As people's financial situations improve, they might opt for higher-quality alternatives. Examples include instant noodles or public transport (where people might switch to owning cars).
Graph of income elasticity of demand for inferior goods

A graph illustrating income elasticity of demand for inferior goods.

Image courtesy of thetutoracademy

2. Duration of Income Change

  • Short-Term vs. Long-Term: Income changes can have varying impacts over different durations. Initially, a surge in income might lead to a significant spike in demand for luxuries. However, as this becomes the new norm, the proportionate increase in demand might taper off.

3. Cultural and Societal Factors

  • Consumer Preferences: Societal norms and cultural values play a role in how people allocate their additional income. In cultures that emphasise frugality or have a strong saving ethic, even significant income rises might not lead to proportional demand increases for luxury goods.

4. Economic Environment

  • Economic Optimism or Pessimism: People's perceptions of the economy's future can influence their spending habits. If the general sentiment is positive, individuals might be more inclined to spend additional income, leading to a higher YED for many goods. On the other hand, during economic downturns or periods of uncertainty, a more conservative approach might prevail, suppressing YED values. The understanding of externalities is essential here, as it affects economic perceptions and consumer spending.
IB Economics Tutor Tip: Understanding YED helps predict market trends and consumer preferences, making it essential for strategic business planning and effective economic policy formulation in varying income scenarios.

5. Availability of Substitutes

  • The presence of alternatives can influence YED. If numerous substitutes exist for a product, its YED might be higher. As people's incomes grow, they have a broader range of choices and might easily transition to other products if they perceive better value or quality elsewhere.

6. Future Expectations

  • If consumers anticipate future changes in their income, either positive or negative, it can influence their current spending behaviour. For instance, if there's an expectation of a recession or job losses in the near future, consumers might become more conservative in their spending, even if their current income hasn't changed.

7. Depth of Market Research

  • Companies that invest in understanding their target demographics and their income elasticity can better predict demand shifts. This knowledge allows for more strategic production and marketing decisions, ensuring that supply aligns more closely with demand. Furthermore, a grasp of the characteristics of public goods can aid in comprehending broader market impacts and consumer behaviour.
Unknown block type "table", specify a component for it in the `components.types` option

A summary table of the determinants of YED.

Graphs of different types of income elasticity of demand

Graphs illustrating different types of income elasticity of demand.

Image courtesy of tutorstips

IB Tutor Advice: Practise calculating YED with diverse examples to enhance your understanding of how income changes affect demand, preparing you for both numerical and essay questions on this topic.

In essence, the Income Elasticity of Demand provides a comprehensive view of how demand patterns shift with income changes. For businesses, it's an invaluable tool for forecasting, pricing strategies, and inventory management. For policymakers, understanding YED can guide decisions on taxation, subsidies, and welfare policies, ensuring that economic policies align with the needs and behaviours of the populace.


While it's common for luxury goods to have a YED greater than one, indicating high responsiveness to income changes, there are exceptions. Some luxury goods might have a YED value less than one due to brand loyalty, perceived necessity, or limited substitutes. For instance, a high-end medication or a luxury brand with a strong loyal customer base might not see a proportionally high increase in demand even if incomes rise. Such products, despite being luxuries, might be viewed as essential or irreplaceable by their consumer base, leading to a YED value less than one.

Governments can leverage YED insights to anticipate how policy changes might impact consumer demand. For instance, if the government is considering a policy that could lead to increased incomes (like tax cuts or wage hikes), understanding which goods have high positive YED can help predict which sectors might benefit most. Conversely, during economic downturns, policies that support industries producing inferior goods (with negative YED) might be more effective. Additionally, in aiming for social objectives, like reducing alcohol consumption, governments might consider the YED of alcohol to predict how demand might change with income fluctuations.

Yes, while YED offers valuable insights, it has limitations. Firstly, YED values are often based on historical data, and past trends might not always predict future behaviours. Secondly, YED doesn't account for other factors like changes in tastes, preferences, or societal norms. Also, sudden economic shocks or unforeseen events (like pandemics) can disrupt predicted demand patterns based on YED. Lastly, YED is a broad measure and might not capture nuances within specific market segments or demographics. Thus, while YED is a useful tool, businesses should use it in conjunction with other market research tools and insights.

While both YED and XED measure responsiveness, they focus on different variables. YED gauges how quantity demanded of a good changes in response to a change in income. In contrast, Cross Elasticity of Demand (XED) measures how the quantity demanded of one good changes in response to a price change in another good. XED helps in understanding the relationship between two goods, whether they are substitutes or complements. For instance, if the price of tea rises and the demand for coffee (a substitute) increases, the XED would be positive. On the other hand, YED focuses solely on the relationship between demand and income levels.

The business cycle, comprising phases like expansion, peak, contraction, and trough, has direct implications on consumers' income levels. During expansion or boom phases, incomes generally rise, and if products have a positive YED, their demand would increase. Conversely, during contraction or recession phases, incomes might decrease, leading to reduced demand for goods with positive YED. However, inferior goods, with negative YED, might see an uptick in demand during economic downturns. Thus, understanding YED can help businesses anticipate demand patterns across different phases of the business cycle and adjust their production and marketing strategies accordingly.

Practice Questions

Define the term 'Income Elasticity of Demand' and explain how it can be used by businesses to predict changes in demand for their products during economic fluctuations.

Income Elasticity of Demand (YED) refers to the responsiveness of the quantity demanded of a particular good or service to a change in consumers' income. It's calculated as the percentage change in quantity demanded divided by the percentage change in income. Businesses can use YED to anticipate how demand for their products might change during economic ups and downs. For instance, if a product has a high positive YED, it's likely a luxury good, and its demand might significantly increase during economic booms but decrease during recessions. Conversely, goods with a negative YED, like inferior goods, might see increased demand during economic downturns.

Differentiate between normal goods and inferior goods in the context of Income Elasticity of Demand. How might businesses adjust their strategies based on the YED of their products?

Normal goods are those for which demand rises as income increases, resulting in a positive YED. Examples include branded clothing or high-end electronics. On the other hand, inferior goods see a decrease in demand as income rises, leading to a negative YED. Examples might include second-hand items or basic public transport. Understanding the YED of their products allows businesses to make strategic decisions. For products with a high positive YED, businesses might focus on premium branding and marketing during economic booms. For products with a negative YED, businesses might look to diversify their offerings or target demographics with lower income levels, especially during economic downturns.

Dave avatar
Written by: Dave
Cambridge University - BA Hons Economics

Dave is a Cambridge Economics graduate with over 8 years of tutoring expertise in Economics & Business Studies. He crafts resources for A-Level, IB, & GCSE and excels at enhancing students' understanding & confidence in these subjects.

Hire a tutor

Please fill out the form and we'll find a tutor for you.

1/2 About yourself
Still have questions?
Let's get in touch.