Chapter 4: The Market Forces of Supply and Demand

    In this chapter, we will explore the fundamental concepts of supply and demand, including how these forces interact to determine market prices and the quantity of goods available in an economy.

Markets and Competition

  • Supply and Demand: These are the forces that drive market economies.

  • Market: A group of buyers and sellers for a particular good or service.

    • Buyers determine demand.

    • Sellers determine supply.

  • Competitive Market: A market with numerous buyers and sellers, each having a negligible impact on the market price.

    • Price and quantity are determined by the interaction of all buyers and sellers.

Perfectly Competitive Market

  • Goods offered for sale are identical.

  • Numerous buyers and sellers exist.

  • No single buyer or seller can influence the market price.

  • Participants are price takers, accepting the market-determined price.

  • At the market price:

    • Buyers can purchase as much as they want.

    • Sellers can sell as much as they want.

Other Markets

  • Monopoly: A market with only one seller who sets the price.

  • Markets exist between perfect competition and monopoly.

Demand

  • Law of Demand: States that, other things being equal, the quantity demanded of a good falls when the price rises, and rises when the price falls.

  • Quantity Demanded: The amount of a good that buyers are willing and able to purchase.

Individual Demand

  • Individual Demand: A single person's demand for a product.

  • Demand Schedule: A table showing the relationship between the price of a good and the quantity demanded.

  • Demand Curve: A graph illustrating the relationship between the price of a good and the quantity demanded; it slopes downward because lower prices increase quantity demanded.

Market Demand

  • Market Demand: The sum of all individual demands for a good or service.

  • Market Demand Curve: Illustrates how the total quantity demanded varies with price, holding other factors constant; it's derived by horizontally summing individual demand curves.

Shifts in the Demand Curve

  • The market demand curve holds other factors constant but isn't stable over time.

  • Demand Curve Shifts:

    • A change that increases the quantity buyers want to purchase at any price shifts the demand curve to the right.

    • A change that decreases the quantity buyers want to purchase at any price shifts the demand curve to the left.

Variables That Influence Buyers

  • Income:

    • Normal Good: An increase in income leads to an increase in demand.

    • Inferior Good: An increase in income leads to a decrease in demand.

  • Prices of Related Goods:

    • Substitutes: Goods used in place of each other; an increase in the price of one increases the demand for the other.

    • Complements: Goods used together; an increase in the price of one decreases the demand for the other.

  • Tastes: Influenced by historical and psychological forces.

  • Expectations: About future income and prices.

  • Number of Buyers: Market demand depends on the number of buyers.

Shifts vs. Movements Along the Demand Curve

  • Movement along the Demand Curve: Change in the price of the good itself.

  • Shifts of the Demand Curve: Changes in income, prices of related goods, tastes, expectations, or the number of buyers.

Supply

  • Law of Supply: States that, other things being equal, the quantity supplied of a good rises when the price rises, and falls when the price falls.

  • Quantity Supplied: The amount of a good that sellers are willing and able to sell.

Individual Supply

  • Individual Supply: A seller’s supply for a product.

  • Supply Schedule: A table that shows the relationship between the price of a good and the quantity supplied.

  • Supply Curve: A graph of the relationship between the price of a good and the quantity supplied; it slopes upward because a higher price increases the quantity supplied.

Market Supply

  • Market Supply: The sum of the supplies of all sellers.

  • Market Supply Curve: Shows how the total quantity supplied varies as the price varies, holding constant all other factors that influence producers’ decisions about how much to sell; derived by horizontally summing individual supply curves.

Shifts in the Supply Curve

  • The market supply curve holds other factors constant but isn't stable over time.

  • Supply Curve Shifts:

    • A change that increases the quantity sellers want to sell at any price shifts the supply curve to the right.

    • A change that decreases the quantity sellers want to sell at any price shifts the supply curve to the left.

Variables That Influence Sellers

  • Input Prices: The supply of a good moves in the opposite direction of the prices of inputs.

  • Technology: Advances in technology increase the supply.

  • Expectations: About future prices.

  • Number of Sellers: Market supply depends on how many sellers there are.

Supply and Demand Together

  • Equilibrium: The point where the quantity buyers are willing and able to buy balances the quantity sellers are willing and able to sell.

  • Equilibrium Price: The price that balances quantity supplied and quantity demanded.

  • Equilibrium Quantity: The quantity supplied and demanded at the equilibrium price.

Surplus

  • Surplus: A situation where the quantity supplied is greater than the quantity demanded.

  • Sellers cut prices, increasing quantity demanded and decreasing quantity supplied, moving the market toward equilibrium.

Shortage

  • Shortage: A situation where the quantity demanded is greater than the quantity supplied.

  • Sellers raise prices, decreasing quantity demanded and increasing quantity supplied, moving the market toward equilibrium.

Law of Supply and Demand

  • Law of Supply and Demand: The price of any good adjusts to bring the quantity supplied and the quantity demanded into balance.

  • Surpluses and shortages are typically temporary because prices move toward equilibrium levels in well-functioning markets.

Analyzing Changes in Equilibrium: Three Steps

  1. Determine whether the event shifts the supply curve, the demand curve, or both.

  2. Decide in which direction the curve shifts.

  3. Use a supply-and-demand diagram to see how the shift changes the equilibrium price and quantity.

Shifts vs. Movements

  • Change in Supply: A shift in the supply curve.

  • Change in Demand: A shift in the demand curve.

  • Change in the Quantity Supplied: A movement along a fixed supply curve.

  • Change in the Quantity Demanded: A movement along a fixed demand curve.

How Prices Allocate Resources

  • In market economies, prices are signals that guide decisions and allocate scarce resources.

  • For every good, the price ensures that supply and demand are in balance.

  • The equilibrium price determines how much buyers consume and how much sellers produce.