The income-consumption line (as explained in the PowerPoint lecture slides for Appendix C) is upward-sloping, what can you conclude about the two goods?
They are both normal goods.
They are both inferior goods.
They are substitutes.
They are complements.
The correct answer and explanation is :
The correct answer is “They are both normal goods.”
Explanation:
The income-consumption line (also known as the income expansion path) shows the relationship between the quantities of two goods that a consumer can purchase as their income changes, assuming that the prices of the goods remain constant. This line represents how consumption of each good varies as a result of changes in income, and its slope provides crucial information about the nature of the goods.
If the income-consumption line is upward-sloping, it indicates that as the consumer’s income increases, they buy more of both goods. This outcome is characteristic of normal goods.
What are normal goods?
Normal goods are goods for which demand increases as income rises. In other words, when a consumer’s income increases, they will typically purchase more of these goods because they can afford to do so. For example, if a person gets a raise and starts buying more of a particular brand of clothing or electronics, those items are normal goods.
Why does an upward-sloping income-consumption line suggest both goods are normal?
An upward-sloping income-consumption line means that as income increases, the quantities of both goods being consumed increase as well. This can only happen if both goods are normal because for inferior goods, the demand decreases as income rises. Inferior goods are those goods that people buy less of as they become wealthier (e.g., cheaper brands or lower-quality goods), and thus an income increase would not lead to higher consumption of those items.
If the goods were substitutes, you would expect a different pattern of consumption behavior, where an increase in income could potentially shift demand from one good to another, depending on the preferences of the consumer. Similarly, if the goods were complements, an increase in income could increase the consumption of both goods, but the relationship would typically be more complex, with the quantities purchased of each good depending on how they are used together (e.g., printers and ink cartridges).
Thus, the upward-sloping income-consumption line conclusively indicates that both goods are normal goods, as both experience higher demand when the consumer’s income increases.