Microeconomics Study Guide: Scarcity, Choice, Market Equilibrium, and Elasticity

Chapter 2: The Economic Problem—Scarcity and Choice

Opportunity Cost, Absolute Advantage, and Comparative Advantage

Understanding how individuals and nations make choices under scarcity is central to microeconomics. Key concepts include opportunity cost, absolute advantage, and comparative advantage, which help explain trade patterns and the benefits of specialization.

• Opportunity Cost: The value of the next best alternative forgone when making a choice.

• Absolute Advantage: The ability of a producer to produce more of a good or service than another producer using the same amount of resources.

• Comparative Advantage: The ability of a producer to produce a good or service at a lower opportunity cost than another producer.

• Example: Consider the following output per hour table:

  	Bread	Cookies
  Dylan	2	6
  Claire	4	8

  • Calculate opportunity cost for each good for each producer.

  • Determine who has absolute and comparative advantage in each good.

  • Specialization should occur according to comparative advantage for gains from trade.

Additional info: Opportunity cost is calculated as the ratio of what is given up to what is gained. For example, Dylan's opportunity cost of 1 bread is 3 cookies (6/2), and for Claire, it is 2 cookies (8/4).

Production Possibility Frontier (PPF)

The PPF illustrates the maximum possible output combinations of two goods that can be produced with available resources and technology.

• X-intercept/Y-intercept: Shows the maximum output of one good when the other is zero.

• Efficient Points: Points on the PPF represent efficient use of resources.

• Inefficient Points: Points inside the PPF indicate underutilization of resources.

• Unattainable Points: Points outside the PPF are not possible given current resources.

• Slope of the PPF: Represents opportunity cost.

• Law of Increasing Opportunity Cost: As production of one good increases, the opportunity cost of producing additional units rises.

Formula:

$\text{Opportunity Cost} = \frac{\text{Loss in Good Y}}{\text{Gain in Good X}}$

Chapter 3: Demand, Supply, and Market Equilibrium

Law of Demand and Demand Curve

The law of demand states that, ceteris paribus, as the price of a good increases, the quantity demanded decreases, and vice versa.

• Movement Along the Demand Curve: Caused by a change in the price of the good.

• Shift of the Demand Curve: Caused by changes in non-price determinants (income, tastes, prices of related goods, expectations).

• Formula:

• $Q_d = f(P, I, T, P_r, E)$

• Example: An increase in consumer income shifts the demand curve for normal goods to the right.

Law of Supply and Supply Curve

The law of supply states that, ceteris paribus, as the price of a good increases, the quantity supplied increases.

• Movement Along the Supply Curve: Caused by a change in the price of the good.

• Shift of the Supply Curve: Caused by changes in non-price determinants (input prices, technology, expectations).

• Formula:

• $Q_s = f(P, P_{inputs}, T, E)$

• Example: A technological improvement shifts the supply curve to the right.

Market Equilibrium

Market equilibrium occurs where quantity demanded equals quantity supplied, determining the equilibrium price and quantity.

• Excess Demand (Shortage): Quantity demanded exceeds quantity supplied; prices tend to rise.

• Excess Supply (Surplus): Quantity supplied exceeds quantity demanded; prices tend to fall.

• Equilibrium Adjustment: Market forces move price toward equilibrium.

Changes in Equilibrium

Three steps to analyzing changes in equilibrium:

1. Determine which curve shifts (demand or supply).

2. Determine the direction of the shift (left or right).

3. Analyze the impact on equilibrium price and quantity.

Chapter 4: Demand and Supply Application

Price Rationing

Price rationing is the process by which the market allocates goods and services to consumers when quantity demanded exceeds quantity supplied.

• The price system automatically distributes scarce goods.

• Example: During a shortage, prices rise until demand equals supply.

Price Ceiling

A price ceiling is a legal maximum set by the government, typically below equilibrium price, creating a shortage.

• Binding Price Ceiling: Set below equilibrium price; causes excess demand.

• Example: Rent control in housing markets.

Consumer Surplus, Producer Surplus, and Deadweight Loss

• Consumer Surplus (CS): The difference between what consumers are willing to pay and what they actually pay.

• Producer Surplus (PS): The difference between the price received by producers and their minimum acceptable price.

• Total Surplus (TS): The sum of consumer and producer surplus; maximized at market equilibrium.

• Deadweight Loss (DWL): The total loss of surplus from underproduction or overproduction due to market inefficiency.

• Example: A binding price ceiling creates DWL by reducing total surplus.

Chapter 5: Elasticity

Price Elasticity of Demand

Price elasticity of demand measures the responsiveness of quantity demanded to changes in price.

• Formula:

• $\text{Price Elasticity of Demand} = \frac{\% \Delta Q_d}{\% \Delta P}$

• Types of Elasticity: Perfectly inelastic, elastic, unitary elastic, perfectly elastic, inelastic.

• Determinants: Availability of substitutes, necessity vs. luxury, proportion of income spent, time horizon.

• Example: Demand for gasoline is typically inelastic in the short run.

Income Elasticity of Demand

Income elasticity of demand measures the responsiveness of quantity demanded to changes in income.

• Formula:

• $\text{Income Elasticity} = \frac{\% \Delta Q_d}{\% \Delta Y}$

• Positive Income Elasticity: Indicates a normal good.

• Negative Income Elasticity: Indicates an inferior good.

• Example: Luxury cars have high positive income elasticity.

Cross-Price Elasticity of Demand

Cross-price elasticity measures the responsiveness of quantity demanded for one good to changes in the price of another good.

• Formula:

• $\text{Cross-Price Elasticity} = \frac{\% \Delta Q_{d, A}}{\% \Delta P_B}$

• Positive Cross-Price Elasticity: Goods are substitutes.

• Negative Cross-Price Elasticity: Goods are complements.

• Example: Butter and margarine are substitutes; butter and bread are complements.

Price Elasticity of Supply

Price elasticity of supply measures the responsiveness of quantity supplied to changes in price.

• Formula:

• $\text{Price Elasticity of Supply} = \frac{\% \Delta Q_s}{\% \Delta P}$

• Types of Elasticity: Perfectly inelastic, elastic, unitary elastic, perfectly elastic, inelastic.

• Determinants: Flexibility of sellers, time horizon (short-run vs. long-run).

• Example: Agricultural products often have inelastic supply in the short run.

Additional info: For exam purposes, you may be asked to identify areas representing CS, PS, TS, or DWL on provided graphs, but not to calculate their values. Also, you should understand the concepts of elasticity for given percentage changes, but not perform calculations.