Practise IB Economics SL 2.5.7 by defining YED, calculating it from data, and applying income elasticity to normal, inferior and sectoral goods with evidence.
Explain why an increase in incomes over time may lead to an increase in demand for some goods but a decrease in demand for other goods.
Answers may include:
- definitions of demand, normal goods, inferior goods
- diagram(s) to show an increase in demand (rightward shift) for normal goods and a decrease in demand (leftward shift) for inferior goods
- explanation of these rightward and leftward shifts
- examples of normal and inferior goods.
Assessment Criteria
Level 0 (0 marks): The work does not meet a standard described by the descriptors below.
Level 1 (1-3 marks): There is little understanding of the specific demands of the question. Relevant economic terms are not defined. There is very little knowledge of relevant economic theory. There are significant errors.
Level 2 (4-6 marks): There is some understanding of the specific demands of the question. Some relevant economic terms are defined. There is some knowledge of relevant economic theory. There are some errors.
Level 3 (7-8 marks): There is understanding of the specific demands of the question. Relevant economic terms are defined. Relevant economic theory is explained and applied. Where appropriate, diagrams are included and applied. Where appropriate, examples are used. There are few errors.
Level 4 (9-10 marks): There is understanding of the specific demands of the question. Relevant economic terms are clearly defined. Relevant economic theory is clearly explained and applied. Where appropriate, diagrams are included and applied effectively. Where appropriate, examples are used effectively. There are no significant errors.