Explain why the concept of the margin is significant in the economic theory of consumer behaviour.

Mark scheme

Marking points from the official mark scheme (May/June 2018). The mark or mark type is shown in brackets.

1. [12] L4 (9-12): for a clear explanation and a sound comment on the relation between the price and the satisfaction obtained, referring to more than one good
2. [12] L3 (7-8): for a less developed answer but which still refers to the equilibrium but probably concentrates on only one good
3. [12] L2 (5-6): for a brief attempt which does not clearly bring out the significance of the marginal analysis
4. [12] L1 (1-4): for an answer that has some basic correct facts but includes irrelevancies and errors of theory
5. [13] L4 (9-13): for an understanding of the link of marginal to allocative efficiency and average to productive efficiency with a conclusion
6. [13] L3 (7-8): for a less accurate understanding – probably evidenced by a weak conclusion of the role of marginal and average in the different efficiencies
7. [13] L2 (5-6): for an unclear answer or one which concentrates on one of the efficiencies
8. [13] L1 (1-4): for an answer that has some basic correct facts but includes irrelevancies and errors of theory