XED

Summary and Exam Tips for XED

Cross Elasticity of Demand (XED) is a subtopic of Microeconomics, which falls under the subject Economics in the IB DP curriculum. XED measures how the quantity demanded of one good responds to a change in the price of another good. It helps in understanding the relationship between two goods or services. XED can be positive for substitutes ($XED > 0$) and negative for complements ($XED < 0$).

For substitutes, a price increase in one good leads to an increase in the demand for another, as seen with Pepsi and Coca-Cola. Strong substitutes have a highly responsive demand, while weak substitutes show less responsiveness. For complements, a price increase in one good results in a decrease in demand for another, exemplified by coffee pods and coffee machines. Strong complements have a less responsive demand, whereas weak complements show greater responsiveness.

Exam Tips

• Understand Definitions: Clearly define XED and differentiate between substitutes and complements.
• Use Examples: Be prepared to illustrate your answers with examples like Pepsi and Coca-Cola for substitutes, and coffee pods and machines for complements.
• Calculate XED: Practice calculating XED using the formula and interpret the results correctly.
• Differentiate Degrees: Know the difference between strong and weak substitutes and complements, and how they affect demand responsiveness.
• Graphical Analysis: Be able to explain and draw demand curve movements and shifts for both substitutes and complements.