Macroeconomics Chapter 4: Demand and Supply
Demand and supply are fundamental forces that determine market prices and quantities, driven by consumer willingness to buy and producer willingness to sell.
Core Principles
- Law of Demand: As price increases, quantity demanded decreases, holding other factors constant.
- Law of Supply: As price increases, quantity supplied increases, holding other factors constant.
- Equilibrium: The point where quantity demanded equals quantity supplied, establishing the market-clearing price and quantity.
- Shifts vs. Movements: Changes in price cause movements along the curves, while changes in other factors (determinants) cause shifts of the entire curves.
Action Steps
- 1. Identify the product or service being analyzed to define the market.
- 2. Determine the current market price and quantity.
- 3. Analyze factors that could shift the demand curve (income, tastes, prices of related goods, expectations, number of buyers).
- 4. Analyze factors that could shift the supply curve (input prices, technology, expectations, number of sellers, taxes/subsidies).
- 5. Predict the new equilibrium price and quantity based on the direction of the shifts.
Formulas
- Demand Curve: $Q_d = f(P, Y, P_s, P_c, T, E)$
- Supply Curve: $Q_s = f(P, P_r, Tech, E, N, T)$
- Equilibrium Condition: $Q_d = Q_s$
Key Terms
- Demand: The relationship between the price of a good or service and the quantity consumers are willing and able to purchase at various prices, holding other factors constant.
- Supply: The relationship between the price of a good or service and the quantity producers are willing and able to sell at various prices, holding other factors constant.
- Equilibrium Price: The price at which the quantity demanded equals the quantity supplied, also known as the market-clearing price.
- Equilibrium Quantity: The quantity of a good or service bought and sold at the equilibrium price.
- Shortage: Occurs when quantity demanded exceeds quantity supplied, typically at a price below equilibrium.
- Surplus: Occurs when quantity supplied exceeds quantity demanded, typically at a price above equilibrium.
Real World Examples
- A heatwave increases demand for air conditioners.: Demand curve shifts right, leading to a higher equilibrium price and quantity for air conditioners.
- A technological advancement lowers the cost of producing smartphones.: Supply curve shifts right, leading to a lower equilibrium price and a higher equilibrium quantity for smartphones.
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