Introduction to Demand and Supply

Definition of Market:
- Any arrangement for bringing buyers and sellers together.
- Different from a marketplace.
Barter System:
  - Goods or services exchanged for other goods or services.
  - Example: Repairing a neighbor's car in exchange for gardening help.
  - Problem: Requires a double coincidence of wants, leading to high transaction costs.
  - Solution: Money is used to conduct trade, simplifying transactions.
Market Economy:
- In a market economy, the price of a good or service is determined through the interaction of demand and supply. - Importance: Understanding the determinants of demand and supply.

Definition of Demand:
  - The relationship between the price of a good and the quantity demanded over a specific time period, ceteris paribus (holding other factors constant).
  - Can be represented by:
    - Demand Schedule: A table showing quantity demanded at different prices.
    - Demand Curve: A graphical representation of a demand schedule.
Law of Demand:
- Principle: Inverse relationship between the price and quantity demanded.
- Explanation: As the price of a good increases, the quantity demanded decreases.
Changes in Demand and Quantity Demanded:
- Change in Quantity Demanded: Refers to a movement along the demand curve, caused by a change in the price of the good.
- Change in Demand: Refers to a shift in the demand curve (from D to D'), indicating a change in demand at every price level. - Example: Increase in demand indicates a larger quantity is demanded at each price.
Market Demand:
  - Total amount demanded by all individuals in the market.
  - Represented as the horizontal summation of individual demand curves.
  - Example Calculation: At a price of $3, two consumers demand 10 and 15 units, respectively (Total Demand = 10 + 15).

Factors Influencing Demand:
  - Tastes and Preferences: Shifts in consumer preferences can increase or decrease demand.
  - Prices of Related Goods:
    - Substitutes: An increase in the price of one good leads to an increase in demand for its substitute.
      - Example: Increase in price of coffee results in higher demand for tea.
    - Complementary Goods: An increase in the price of one good leads to a decrease in demand for another good that is consumed together.
      - Example: Increase in the price of DVDs decreases demand for DVD players.   - Income Levels: Typically, as income increases, demand for most goods increases as well.
  - Number of Consumers: An increase in the number of consumers leads to an increase in demand.
  - Expectations of Future Prices: If consumers expect prices to rise in the future, they may increase current demand.

Definition of Supply:
  - The relationship between the price of a good and the quantity supplied over a specific time period, ceteris paribus.   - Can be represented by:
    - Supply Curve: A graphical representation showing the relationship between price and quantity supplied.
    - Supply Schedule: A table showing price and corresponding quantity supplied.
Law of Supply:
- Principle: Direct relationship between the price of a good and the quantity supplied; as price increases, quantity supplied also increases. - Supply curves are generally upward sloping.
Changes in Supply and Quantity Supplied:
- Change in Quantity Supplied: A movement along the supply curve due to a change in the price of the good.
- Change in Supply: Shifts in the supply curve; a rightward shift indicates an increase in supply at the same price, and a leftward shift indicates a decrease in supply.
Market Supply:
- The market supply curve is the summation of all individual supply curves from producers in the market.

Factors Influencing Supply:
  - Prices of Resources: Higher resource prices reduce profitability, leading to lower quantity supplied at each price (leftward shift in supply curve).
  - Technology and Productivity: Advances in technology can increase productivity, lowering production costs and increasing supply.
  - Producer Expectations: Expectations of future product prices can affect current supply levels.
  - Number of Producers: Increased competition in the market leads to increased supply.
  - Prices of Related Goods and Services: The supply of a good may be affected by prices of goods that are produced in conjunction with it.

Definition of Equilibrium:
- The point where the market demand and supply curves intersect. This defines the equilibrium price and quantity. - Example: Equilibrium price = $3 at a quantity of 60 units, where Demand = Supply (D = S).
Surplus and Shortage:
- At a price above $3: A surplus occurs when quantity supplied (S) exceeds quantity demanded (D). - Response: Firms lower prices until surplus is eliminated, moving towards $3. - At a price below $3: A shortage occurs when quantity demanded (D) exceeds quantity supplied (S). - Response: Producers raise prices until the shortage is resolved, moving towards $3.

Effects of Demand Increase:
- An increase in demand raises both market supply (S) and demand (D), resulting in a new equilibrium.
Effects of Demand Decrease:
- A decrease in demand lowers both market supply (S) and demand (D), resulting in a new equilibrium.
Effects of Supply Increase:
- An increase in supply results in lower prices and higher quantity sold.
Effects of Supply Decrease:
- A decrease in supply leads to higher prices but lower quantity sold.

Price Ceilings:
  - Definition: A legally mandated maximum price imposed by the government on a product.   - Illustration:
    - If a price ceiling is set below the market-clearing price, e.g., the price Pc, this results in illegal market-clearing price Pe.
    - Scenario: At price Pc, buyers wish to purchase quantity Q4, while sellers are willing to sell only Q1, leading to a market shortage (QD > QS).   - Example: Rent controls and regulated food prices are examples of price ceilings causing shortages.
Price Floors:
- Definition: A legally mandated minimum price set by the government. - Illustration:
- Example of a price floor at price Pf, where sellers wish to sell quantity Q2, but buyers are only willing to buy Q3. - Result: Because the price is above the equilibrium price, it leads to a surplus in the market (QS > QD). - Example: Minimum wage laws serve as a price floor for labor, ensuring wages do not fall below a certain level.