1. Individual and market demand
CHAPTER 4
Individual and market demand

2. Outcomes Derive individual demand curve
Effect of change in price and income on the demand curve
Market demand curve
Consumer surplus
Effects of network externalities

3. CHANGES IN EQUILIBRIUM
How does the equilibrium position change if: 1. Consumer’s income change OR 2. Price of one of the goods change

4. Income Effect on Consumer Equilibrium
Change in income, all prices remaining constant.
If prices of goods, tastes and preferences of the consumer remain constant and there is a change in income, it will directly affect consumer’s equilibrium.
A rise in the income of a consumer shifts the Budget line to the right upward on higher IC.
A fall in the income shifts the Budget line to the left side on lower IC.

5. Income Effect on Consumer Equilibrium
A rise in the Income: Consumer can buy more of both commodities = Higher level of satisfaction and increase in equilibrium.
A fall in the Income = Consumer buy less of both the commodities = Lower level of satisfaction and decrease in equilibrium.
The line which touches all the consumer equilibrium points = Income Consumption Curve (ICC).
ICC = The consumption of two goods is affected by change in income when prices are constant.

6. Income Effect on Consumer Equilibrium

7. Price Effect on Consumer Equilibrium
Price Effect = A result of change in the price of one commodity while price of other good and income of the consumer remain constant.
The change in demand in response to a change in price of a commodity, other things remaining the same (Ceteris Paribus), is called Price effect.
If we draw a line which touches all the consumer equilibrium points so we will get Price Consumption Curve (PCC).
PCC = The consumption of good X changes, as its price changes, remaining constant the price of good Y and the income of the consumer.

8. Price Effect on Consumer Equilibrium

9. NORMAL AND INFERIOR GOODS
Normal goods = Willing and able to buy anything with an income increases or the price decreases
Example: NEW clothing, NEW car, NEW computer.
Inferior goods = Comparable to the normal good. More willing to purchase as income decreases or the price increases
Example: USED clothing, USED car, USED computer i.e.  income and  quantity.

10. Effect on an inferior good

11. Engel Curves
Curve relating the quantity of a good consumed to income.

12. Income and substitution effects
 Price:
Consumer will buy more of cheaper good and less of relatively more expensive good.
One good cheaper  Consumer enjoy increase in real purchasing power.
Two effects occur simultaneously

13. Income and substitution effects: Normal Good

14. Substitution effect Income effect Total effect
Change in consumption of a good with a change in its price, with the level of utility held constant.
Income effect
Change in consumption of a good resulting from an increase in purchasing power, with relative prices held constant.
Total effect
Total Effect (F1F2) = Substitution effect (F1E) + Income Effect (EF2)

15. Income and substitution effects: Inferior Goods

16. Special Case: GIFFEN GOODS
Theoretically possible (but doubted):
Good whose demand curve slopes upward because the negative income effect is larger than the substitution effect.

17. Market demand curve
Discussed in Chapter 2

18. ELASTICITY: Recap
Inelastic demand: Quantity demanded is relatively unresponsive to changes in price, e.g.. Gasoline
Elastic demand: Expenditure on the product decreases as the price goes up, e.g.. Beef
Isoelastic demand: Demand curve with constant price elasticity.
Special isoelastic demand curve: unit-elastic demand curve -1.

19. Consumer Surplus Definition: Difference between
Willing to pay for a good, and;
Amount actually paid
Calculate from the demand curve

22. Network externalities
Assumption: Demand for a good are independent of one another.
However, for some goods demand depends on the demand of other people.
Network externalities exist.
Definition:
Situation in which each individual’s demand,
depends on the purchases of other individuals
Positive or negative
Positive = Quantity of good demand by consumer increase in response to the growth in purchases of other consumers.
Negative = Vice versa, demand decreases

23. Network externalities - The bandwagon effect
Positive network externality
Definition: Consumer wishes to possess a good in part because others do, e.g.. Toys: Playstation, Xbox
Exploited by marketers

25. Network externalities - Snob effect
Negative externality.
Definition:
Consumer wishes to own an exclusive or unique good e.g.. Works of art, sports car
Prestige, status and exclusivity