💵Principles of Macroeconomics Unit 3 – Demand and Supply

Key Concepts

• Supply represents the quantity of a good or service that producers are willing and able to offer at various prices
• Demand refers to the quantity of a good or service that consumers are willing and able to purchase at different prices
• Market equilibrium occurs when the quantity supplied equals the quantity demanded, resulting in a stable price
• Price elasticity measures the responsiveness of supply or demand to changes in price (elastic, inelastic, unit elastic)
• Shortages arise when the quantity demanded exceeds the quantity supplied at a given price
• Surpluses occur when the quantity supplied exceeds the quantity demanded at a given price
• Price controls, such as price ceilings and price floors, can distort market outcomes and lead to inefficiencies

Supply and Demand Curves

• Supply curves are typically upward-sloping, indicating that as price increases, producers are willing to supply more of a good or service
  • This relationship is known as the law of supply
  • Factors influencing supply include input prices, technology, expectations, and the number of sellers
• Demand curves are typically downward-sloping, indicating that as price increases, consumers are willing to purchase less of a good or service
  • This relationship is known as the law of demand
  • Factors influencing demand include income, preferences, prices of related goods, expectations, and the number of buyers
• The intersection of the supply and demand curves determines the market equilibrium price and quantity
• Movements along the supply or demand curve occur when there is a change in price, holding other factors constant
• Shifts in the supply or demand curve happen when factors other than price change, such as changes in income or production costs

Market Equilibrium

• Market equilibrium is a state where the quantity supplied equals the quantity demanded at a given price
• At equilibrium, there is no tendency for the price or quantity to change, assuming no external factors intervene
• The equilibrium price, also known as the market-clearing price, is the price at which the market is in balance
• Equilibrium quantity is the quantity bought and sold at the equilibrium price
• If the market price is above the equilibrium price, a surplus will occur, putting downward pressure on the price
• If the market price is below the equilibrium price, a shortage will occur, putting upward pressure on the price
• The market tends to naturally move towards equilibrium through the forces of supply and demand

Shifts vs. Movements

• Movements along the supply or demand curve occur when there is a change in price, holding other factors constant
  • A movement along the demand curve is called a change in quantity demanded
  • A movement along the supply curve is called a change in quantity supplied
• Shifts in the supply or demand curve happen when factors other than price change
  • A shift in the demand curve is called a change in demand
    • Factors causing a shift in demand include changes in income, preferences, prices of related goods, and expectations
  • A shift in the supply curve is called a change in supply
    • Factors causing a shift in supply include changes in input prices, technology, expectations, and the number of sellers
• Shifts in the curves lead to a new equilibrium price and quantity

Elasticity

• Elasticity measures the responsiveness of supply or demand to changes in price or other variables
• Price elasticity of demand (PED) is the percentage change in quantity demanded divided by the percentage change in price
  • If PED > 1, demand is elastic (responsive to price changes)
  • If PED < 1, demand is inelastic (less responsive to price changes)
  • If PED = 1, demand is unit elastic (proportional change in quantity demanded equals proportional change in price)
• Price elasticity of supply (PES) is the percentage change in quantity supplied divided by the percentage change in price
  • If PES > 1, supply is elastic (responsive to price changes)
  • If PES < 1, supply is inelastic (less responsive to price changes)
  • If PES = 1, supply is unit elastic (proportional change in quantity supplied equals proportional change in price)
• Income elasticity of demand measures the responsiveness of demand to changes in consumer income
• Cross-price elasticity of demand measures the responsiveness of demand for one good to changes in the price of another good

Price Controls and Market Interventions

• Price controls are government-imposed restrictions on the prices that can be charged for goods or services
• Price ceilings are legal maximum prices set below the market equilibrium price
  • Can lead to shortages, black markets, and reduced quality
  • Examples include rent controls and price caps on essential goods during emergencies
• Price floors are legal minimum prices set above the market equilibrium price
  • Can lead to surpluses and inefficiencies
  • Examples include minimum wages and agricultural price supports
• Taxes and subsidies can also affect market outcomes
  • Taxes increase the cost of production, shifting the supply curve to the left and leading to higher prices and lower quantities
  • Subsidies decrease the cost of production, shifting the supply curve to the right and leading to lower prices and higher quantities

Real-World Applications

• Understanding supply and demand is crucial for businesses when making production and pricing decisions
  • Firms must consider factors affecting supply and demand to maximize profits and remain competitive
• Policymakers use the concepts of supply and demand to analyze the potential impacts of regulations, taxes, and subsidies on markets
  • Price controls, such as rent control and minimum wages, can have unintended consequences that need to be considered
• Supply and demand analysis can help explain price fluctuations in various markets, such as housing, labor, and commodities
  • Changes in factors affecting supply and demand, such as interest rates or geopolitical events, can lead to significant price movements
• The principles of supply and demand apply to international trade and exchange rates
  • Differences in supply and demand across countries influence the flow of goods, services, and capital

Common Misconceptions

• The equilibrium price is not always the "fair" price, as fairness is a subjective concept that may consider factors beyond supply and demand
• Price controls do not address the underlying causes of shortages or surpluses and often lead to unintended consequences
• Elasticity is not the same as slope; elasticity measures responsiveness, while slope measures the rate of change
• A shift in the supply or demand curve does not necessarily mean that the equilibrium price and quantity will change in the same direction
  • The ultimate effect depends on the relative magnitude of the shifts
• Supply and demand analysis assumes ceteris paribus (all else being equal), which may not always hold in real-world situations with multiple changing variables
• The concepts of supply and demand are not limited to perfectly competitive markets; they can be applied to various market structures with some modifications
• Elasticity values can change over time as market conditions evolve, so they should be regularly re-evaluated