Demand and Supply: Foundations of Market Analysis

Markets and Prices

Introduction to Markets

Markets are arrangements that allow buyers and sellers to exchange goods and services. Prices emerge from the interactions of demand and supply in these markets, serving as signals that allocate resources efficiently.

• Market: Any arrangement that enables buyers and sellers to get information and do business with each other.

• Price: The amount of money exchanged for a good or service.

• Relative Price: The price of one good in comparison to another, reflecting opportunity cost.

• Example: The price of an energy bar is $2, and the price of a bottle of water is $1. The relative price of an energy bar is 2 bottles of water per bar.

Demand

Definition and Law of Demand

Demand refers to the quantity of a good or service that consumers are willing and able to buy at various prices during a given period, ceteris paribus (all else equal).

• Law of Demand: Other things remaining the same, the higher the price of a good, the smaller is the quantity demanded; the lower the price, the greater the quantity demanded.

• Reasons for Law of Demand:

  • Substitution Effect: When the price of a good rises, people switch to substitutes, reducing quantity demanded.

  • Income Effect: A higher price reduces consumers' real income, decreasing quantity demanded.

Demand Curve and Schedule

The demand curve is a graphical representation of the relationship between the price of a good and the quantity demanded. The demand schedule is a table showing this relationship.

Price ($)	Quantity Demanded
1.00	15
1.50	12
2.00	10
2.50	8
3.00	6

The demand curve slopes downward, reflecting the law of demand.

Changes in Demand vs. Changes in Quantity Demanded

• Change in Quantity Demanded: Movement along the demand curve due to a change in the good's own price.

• Change in Demand: Shift of the entire demand curve due to changes in non-price determinants (e.g., income, tastes, prices of related goods).

Determinants of Demand

• Prices of related goods (substitutes and complements)

• Expected future prices

• Income (normal and inferior goods)

• Expected future income and credit

• Population

• Preferences

Change in Demand	Effect on Demand
Increase in income (normal good)	Demand increases
Increase in price of substitute	Demand increases
Increase in price of complement	Demand decreases
Increase in population	Demand increases

Supply

Definition and Law of Supply

Supply refers to the quantity of a good or service that producers are willing and able to sell at various prices during a given period, ceteris paribus.

• Law of Supply: Other things remaining the same, the higher the price of a good, the greater is the quantity supplied; the lower the price, the smaller the quantity supplied.

Supply Curve and Schedule

The supply curve shows the relationship between the price of a good and the quantity supplied. The supply schedule is a table showing this relationship.

Price ($)	Quantity Supplied
1.00	2
1.50	4
2.00	6
2.50	8
3.00	10

The supply curve slopes upward, reflecting the law of supply.

Minimum Supply Price

• The minimum price at which a producer is willing to sell a good, covering the marginal cost of production.

Changes in Supply vs. Changes in Quantity Supplied

• Change in Quantity Supplied: Movement along the supply curve due to a change in the good's own price.

• Change in Supply: Shift of the entire supply curve due to changes in non-price determinants (e.g., input prices, technology).

Determinants of Supply

• Prices of factors of production

• Prices of related goods produced

• Expected future prices

• Number of suppliers

• Technology

• State of nature

Change in Supply	Effect on Supply
Decrease in input prices	Supply increases
Improved technology	Supply increases
Increase in number of suppliers	Supply increases
Expected higher future prices	Supply decreases now

Market Equilibrium

Equilibrium Price and Quantity

Market equilibrium occurs where the quantity demanded equals the quantity supplied. The price at this point is the equilibrium price, and the quantity is the equilibrium quantity.

• At prices above equilibrium, there is a surplus (excess supply).

• At prices below equilibrium, there is a shortage (excess demand).

Price ($)	Quantity Demanded	Quantity Supplied	Surplus/Shortage
1.00	15	2	Shortage
2.00	10	6	Shortage
2.50	8	8	Equilibrium
3.00	6	10	Surplus

Price Adjustments

• If there is a surplus, price falls toward equilibrium.

• If there is a shortage, price rises toward equilibrium.

Predicting Changes in Price and Quantity

Effects of Changes in Demand and Supply

Shifts in demand and supply curves lead to changes in equilibrium price and quantity.

• Increase in Demand: Raises both equilibrium price and quantity.

• Decrease in Demand: Lowers both equilibrium price and quantity.

• Increase in Supply: Lowers equilibrium price but raises equilibrium quantity.

• Decrease in Supply: Raises equilibrium price but lowers equilibrium quantity.

Simultaneous Changes

When both demand and supply change, the effect on equilibrium price and quantity depends on the magnitude and direction of the shifts.

Change in Demand	Change in Supply	Effect on Price	Effect on Quantity
Increase	Increase	Indeterminate	Increase
Decrease	Decrease	Indeterminate	Decrease
Increase	Decrease	Increase	Indeterminate
Decrease	Increase	Decrease	Indeterminate

Examples and Applications

• Global Market for Crude Oil: Changes in global demand and supply can cause large swings in oil prices and quantities traded.

• Market for Strawberries: Weather events affecting supply can shift the supply curve, impacting equilibrium price and quantity.

Key Formulas

• Relative Price: $\text{Relative Price of Good A} = \frac{\text{Money Price of Good A}}{\text{Money Price of Good B}}$

Summary Table: Demand and Supply Determinants

Determinant	Demand	Supply
Own Price	Movement along curve	Movement along curve
Income	Shift (normal/inferior goods)	No effect
Prices of Related Goods	Shift (substitutes/complements)	Shift (substitutes/complements in production)
Expected Future Prices	Shift	Shift
Population/Number of Suppliers	Shift	Shift
Preferences/Technology	Shift	Shift

Additional info: This summary expands on the textbook content by providing structured tables, explicit definitions, and formula formatting for clarity and exam preparation.