Microeconomics Study Guide: Core Concepts and Market Structures

Ch. 1 What is Economics

Introduction to Economics

Economics is the study of how individuals, firms, and societies allocate scarce resources to satisfy unlimited wants. It is divided into two main branches: microeconomics (the study of individual agents and markets) and macroeconomics (the study of the economy as a whole).

• Scarce Resource: A resource with limited availability relative to the demand for it.

• Normative Statement: A statement that expresses a value judgment about whether a situation is desirable or undesirable.

• Positive Statement: A statement that can be tested and validated; it describes the world as it is.

• Three Principles of Economics:

  • People face trade-offs

  • The cost of something is what you give up to get it (opportunity cost)

  • Rational people think at the margin

• Free Rider Problem: Occurs when individuals benefit from resources or services without paying for them, leading to under-provision of those goods.

Example: Public radio is often underfunded because people can listen without donating (free riding).

Ch. 3 Optimization

Cost-Benefit Analysis and Opportunity Cost

Optimization involves making the best choice possible with given information. Economists use cost-benefit analysis to compare the costs and benefits of different actions.

• Cost-Benefit Analysis: A process of comparing the costs and benefits of a decision.

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

• Marginal Analysis: Examining the additional benefits and costs of a decision.

• Optimization Techniques: Total value and marginal analysis methods are used to determine the optimal choice.

Formula:

$\text{Net Benefit} = \text{Total Benefit} - \text{Total Cost}$

Example: Choosing between two jobs by comparing salary (benefit) and commute time (cost).

Ch. 4 Supply, Demand, and Equilibrium

Perfectly Competitive Markets

In perfectly competitive markets, many buyers and sellers interact, and no single agent can influence the market price.

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

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

• Law of Demand: As price falls, quantity demanded rises, ceteris paribus.

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

• Supply Schedule: A table showing the relationship between price and quantity supplied.

• Law of Supply: As price rises, quantity supplied rises, ceteris paribus.

• Equilibrium: The point where quantity demanded equals quantity supplied.

Formula:

$Q_d = Q_s$ (at equilibrium)

Example: If the price of apples is too high, there will be excess supply (surplus); if too low, excess demand (shortage).

Ch. 5 Consumer Behavior

The Budget Constraint

The budget constraint represents all combinations of goods and services that a consumer can afford given their income and the prices of goods.

• Budget Set: All possible combinations of goods a consumer can afford.

• Budget Constraint: The line representing the maximum affordable combinations.

• Income and Expenditure: The equality between income and expenditure defines the budget constraint.

Formula:

$P_x X + P_y Y = I$

where $P_x$ and $P_y$ are prices of goods X and Y, and $I$ is income.

Solving the Consumer's Problem

• Utility: The satisfaction or pleasure derived from consuming goods and services.

• Indifference Curve: A curve showing combinations of goods that give the consumer equal satisfaction.

• Marginal Utility: The additional satisfaction from consuming one more unit of a good.

Example: A consumer chooses the combination of pizza and soda that maximizes utility given their budget.

Elasticity

• Price Elasticity of Demand: Measures how much quantity demanded responds to a change in price.

• Cross Price Elasticity: Measures how the quantity demanded of one good responds to a change in the price of another good.

• Income Elasticity: Measures how quantity demanded responds to a change in income.

Formula:

$\text{Price Elasticity of Demand} = \frac{\% \text{ change in quantity demanded}}{\% \text{ change in price}}$

Ch. 6 Producer Behavior

Production and Costs

• Production: The process of transforming inputs into outputs.

• Marginal Product: The additional output from using one more unit of input.

• Fixed Cost: Costs that do not vary with output.

• Variable Cost: Costs that change with output.

• Marginal Cost (MC): The increase in total cost from producing one more unit.

• Average Total Cost (ATC): Total cost divided by output.

Formulas:

$MC = \frac{\Delta TC}{\Delta Q}$

$ATC = \frac{TC}{Q}$

The Firm's Problem

• Objective: Typically, to maximize profit.

• Revenue: Total income from sales ($TR = P \times Q$).

• Profit: $\text{Profit} = \text{Total Revenue} - \text{Total Cost}$

Ch. 7 Efficiency of Perfectly Competitive Markets

Market Efficiency and Surplus

• Invisible Hand: The concept that self-interested actions can lead to socially desirable outcomes.

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

• Producer Surplus: The difference between the price received and the minimum price at which producers are willing to sell.

• Social Surplus: The sum of consumer and producer surplus.

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

Example: Price floors and ceilings can create deadweight loss by preventing markets from reaching equilibrium.

Ch. 8 Trade

Production Possibilities and Trade

• Production Possibilities Curve (PPC): Shows the maximum combinations of goods that can be produced with available resources.

• Absolute Advantage: The ability to produce more of a good with the same resources.

• Comparative Advantage: The ability to produce a good at a lower opportunity cost.

• Terms of Trade: The rate at which one good is exchanged for another.

Example: If country A can produce either 10 cars or 20 computers, and country B can produce 5 cars or 15 computers, country A has an absolute advantage in both, but a comparative advantage in cars.

International Trade

• World Price: The price of a good on the international market.

• Importing/Exporting: Determined by comparing domestic price to world price.

• Tariffs: Taxes on imports that can create winners (domestic producers) and losers (consumers).

Ch. 9 Externalities, Public Goods, and Common Pool Resources

Externalities

• Externality: A cost or benefit imposed on a third party not involved in a transaction.

• Positive Externality: Benefits others (e.g., education).

• Negative Externality: Imposes costs (e.g., pollution).

• Market Failure: When externalities cause markets to allocate resources inefficiently.

• Corrective Taxes/Subsidies: Used to internalize externalities.

Formulas:

$MSC = MPC + MEC$

$MSB = MPB + MEB$

where MSC = Marginal Social Cost, MPC = Marginal Private Cost, MEC = Marginal External Cost, MSB = Marginal Social Benefit, MPB = Marginal Private Benefit, MEB = Marginal External Benefit.

Public Goods and Common Pool Resources

• Public Good: Non-excludable and non-rivalrous (e.g., national defense).

• Free Rider Problem: People benefit without paying, leading to under-provision.

• Common Pool Resource: Non-excludable but rivalrous (e.g., fisheries).

• Tragedy of the Commons: Overuse of common resources due to lack of property rights.

Ch. 11 Markets for Factors of Production

Factors of Production and Labor Markets

• Factors of Production: Inputs used to produce goods and services (land, labor, capital).

• Marginal Product of Input: Additional output from one more unit of input.

• Labor-Leisure Trade-off: The choice between working (earning income) and leisure (non-work time).

• Wage Inequality: Differences in wages due to skills, education, discrimination, and other factors.

Formula:

$\text{Value of Marginal Product} = \text{Marginal Product} \times \text{Price of Output}$

Ch. 12 Monopoly

Monopoly and Market Power

• Monopoly: A market with a single seller and no close substitutes.

• Market Power: The ability to influence price.

• Barriers to Entry: Legal or natural obstacles that prevent new firms from entering.

• Price Discrimination: Charging different prices to different consumers for the same good.

• Deadweight Loss: Inefficiency caused by monopoly pricing.

Formula:

$MR = MC$ (profit-maximizing condition for monopoly)

Ch. 14 Oligopoly and Monopolistic Competition

Oligopoly

• Oligopoly: A market structure with a few large firms that have market power.

• Game Theory: The study of strategic interactions among firms.

• Nash Equilibrium: A situation where no player can benefit by changing strategy while others keep theirs unchanged.

Monopolistic Competition

• Monopolistic Competition: Many firms sell similar but not identical products.

• Product Differentiation: Each firm offers a product slightly different from its competitors.

• Downward Sloping Demand: Firms face a downward sloping demand curve due to product differentiation.

Table: Summing up the Different Market Structures

Market Structure	# of Firms	Type of Good	Barriers to Entry	Price Control	Demand Curve	Long-Run Profits	Efficiency
Perfect Competition	Many	Homogeneous	None	Price Taker	Firm Demand Curve: Perfectly Elastic	Zero	Maximized
Monopolistic Competition	Many	Differentiated	None	Some	Downward Sloping	Zero	Not Maximized
Oligopoly	Few	Homogeneous or Differentiated	Some	Some	Downward Sloping	Positive	Not Maximized
Monopoly	One	Unique	High	Price Maker	Market Demand Curve	Positive	Not Maximized

Additional info: Table summarizes the main characteristics of the four primary market structures in microeconomics, including number of firms, product type, barriers to entry, price control, demand curve, long-run profits, and efficiency.