Principles of Microeconomics: Exam 1 Study Guide (Chapters 1-6)

Principles of Microeconomics: Exam 1 Study Guide

Chapter 1: The Principles and Practice of Economics

This chapter introduces foundational concepts in microeconomics, focusing on how individuals and societies allocate scarce resources.

• Economic Agent: Any individual or group making economic decisions (e.g., consumers, firms).

• Scarce Resources: Limited resources available to meet unlimited wants.

• Scarcity: The fundamental economic problem of having limited resources to satisfy unlimited needs.

• Economics: The study of how people manage resources and make choices.

• Microeconomics vs. Macroeconomics: Microeconomics studies individual agents and markets; macroeconomics studies the economy as a whole.

• Optimization: Making the best possible choice given constraints.

• Equilibrium: A situation where no agent has an incentive to change their behavior.

• Empiricism: Using data to test economic theories.

• Trade-off: The idea that choosing one thing means giving up something else.

• Opportunity Cost: The value of the next best alternative foregone.

• Cost-Benefit Analysis: Comparing the costs and benefits of a decision.

Example: Choosing to attend college involves a trade-off between tuition costs and potential future earnings.

Chapter 2: Economic Science—Using Data and Models to Understand the World

This chapter covers the scientific approach to economics, including the use of models and empirical evidence.

• Scientific Method: Systematic process for testing hypotheses using data.

• Model: Simplified representation of reality used to analyze economic situations.

• Data: Information used to test models and hypotheses.

• Empirical Evidence: Observations and measurements used to support or refute economic theories.

• Hypotheses: Proposed explanations that can be tested.

• Average (Mean): Sum of values divided by the number of values.

• Causation vs. Correlation: Causation implies one variable causes another; correlation means variables move together but not necessarily causally.

• Variable: Any characteristic that can take different values.

• Positive vs. Negative Correlation: Positive: variables move in the same direction; negative: variables move in opposite directions.

• Omitted Variable: A variable not included in analysis that may affect results.

• Reverse Causality: When it is unclear which variable causes the other.

• Experiments: Controlled studies to test hypotheses.

• Randomization: Assigning subjects randomly to groups to eliminate bias.

• Natural Experiment: An event that allows for observation of economic behavior without controlled intervention.

Example: Studying the effect of minimum wage increases on employment using data from different states.

Chapter 3: Optimization—Trying to Do the Best You Can

This chapter explores how individuals and firms make optimal decisions using marginal analysis and comparative statics.

• Optimization in Levels: Choosing the best option by comparing total net benefits across alternatives.

• Optimization in Differences: Comparing the change in net benefits from one option to another.

• Behavioral Economics: Studies how psychological factors affect economic decisions.

• Optimum: The best feasible choice.

• Comparative Statics: Analysis of how changes in parameters affect the optimum.

• Marginal Analysis: Examining the additional benefit or cost from a small change in decision.

• Marginal Cost: The cost of producing one more unit. $MC = \frac{\Delta TC}{\Delta Q}$

• Optimization at the Margin: Optimal decisions are made where marginal benefit equals marginal cost.

Example: A firm decides how many workers to hire by comparing the marginal cost of labor to the marginal benefit (output).

Chapter 4: Demand, Supply, and Equilibrium

This chapter analyzes how markets function, focusing on demand, supply, and the determination of equilibrium price and quantity.

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

• Market Price: The price at which goods are bought and sold.

• Perfectly Competitive Market: Many buyers and sellers, no single agent can influence price.

• Price-Taker: An agent who accepts the market price as given.

• Quantity Demanded: Amount of a good buyers are willing to purchase at a given price.

• Demand Schedule: Table showing quantity demanded at different prices.

• Demand Curve: Graphical representation of the demand schedule.

• Inverse Relationship: As price increases, quantity demanded decreases (law of demand).

• Law of Demand: $Q_d = f(P)$ where $Q_d$ decreases as $P$ increases.

• Willingness to Pay: Maximum price a buyer will pay for a good.

• Marginal Benefit: Additional benefit from consuming one more unit.

• Diminishing Marginal Benefit: Marginal benefit decreases as consumption increases.

• Aggregation: Summing individual demand curves to obtain market demand.

• Demand Curve Shifts: Caused by changes in income, prices of related goods, tastes, etc.

• Normal vs. Inferior Good: Normal goods: demand increases with income; inferior goods: demand decreases with income.

• Substitutes vs. Complements: Substitutes: goods used in place of each other; complements: goods used together.

• Quantity Supplied: Amount sellers are willing to sell at a given price.

• Supply Schedule: Table showing quantity supplied at different prices.

• Supply Curve: Graphical representation of the supply schedule.

• Law of Supply: $Q_s = f(P)$ where $Q_s$ increases as $P$ increases.

• Willingness to Accept: Minimum price a seller will accept.

• Market Supply Curve: Sum of individual supply curves.

• Input (Factor of Production): Resources used to produce goods (e.g., labor, capital).

• Supply Curve Shifts: Caused by changes in input prices, technology, etc.

• Competitive Equilibrium: Where quantity demanded equals quantity supplied.

• Competitive Equilibrium Price: Price at which market clears.

• Competitive Equilibrium Quantity: Quantity at which market clears.

• Excess Supply: Quantity supplied exceeds quantity demanded (surplus).

• Excess Demand: Quantity demanded exceeds quantity supplied (shortage).

• Government Fixing Market Price: Price controls (e.g., price floors, price ceilings).

• Shifts in Demand and/or Supply: Affect equilibrium price and quantity.

Example: An increase in consumer income shifts the demand curve for normal goods to the right, raising equilibrium price and quantity.

Chapter 5: Consumers and Incentives

This chapter examines how consumers make choices, the role of budget constraints, and the concept of elasticity.

• Buyer's Problem: How to allocate limited income across goods to maximize utility.

• Budget Constraint: The set of all bundles a consumer can afford. $P_x X + P_y Y \leq I$

• Budget Set: All affordable combinations of goods.

• Affordable vs. Not Affordable: Bundles within the budget set are affordable; outside are not.

• Slope of Budget Line and Opportunity Cost: Slope indicates the rate at which one good can be traded for another.

• Total Benefit: Overall satisfaction from consumption.

• Marginal Benefit: Additional satisfaction from consuming one more unit.

• Marginal Benefit per Dollar: Marginal benefit divided by price.

• "Bang for Buck": Maximizing marginal benefit per dollar spent.

• Criteria for Optimal Bundle: Marginal benefit per dollar equal across goods.

• Why the Demand Curve is Downward Sloping: Diminishing marginal benefit and substitution effect.

• Consumer Surplus: Difference between willingness to pay and actual price paid.

• Price Elasticity of Demand: Measures responsiveness of quantity demanded to price changes. $\varepsilon_d = \frac{\%\,\text{change in } Q_d}{\%\,\text{change in } P}$

• Perfectly Elastic Demand: $\varepsilon_d = \infty$

• Elastic Demand: $\varepsilon_d > 1$

• Unit Elastic Demand: $\varepsilon_d = 1$

• Inelastic Demand: $\varepsilon_d < 1$

• Perfectly Inelastic Demand: $\varepsilon_d = 0$

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

• Relationship Between Price Elasticity and Revenue: Elastic demand: price increase lowers revenue; inelastic demand: price increase raises revenue.

• Cross-Price Elasticity of Demand: Measures responsiveness of demand for one good to price changes in another. $\varepsilon_{xy} = \frac{\%\,\text{change in } Q_x}{\%\,\text{change in } P_y}$

• Income Elasticity of Demand: Measures responsiveness of demand to income changes. $\varepsilon_I = \frac{\%\,\text{change in } Q}{\%\,\text{change in } I}$

• Normal and Inferior Goods: Normal goods: positive income elasticity; inferior goods: negative income elasticity.

Example: If the price of coffee rises and demand for tea increases, tea and coffee are substitutes (positive cross-price elasticity).

Chapter 6: Sellers and Incentives

This chapter focuses on firms, production, costs, and the supply side of the market.

• Firm: An organization that produces goods or services.

• Production: The process of creating goods and services.

• Physical Capital: Tangible assets used in production (e.g., machinery).

• Short Run: Period in which at least one input is fixed.

• Long Run: Period in which all inputs can be varied.

• Fixed Factors of Production: Inputs that cannot be changed in the short run.

• Variable Factors of Production: Inputs that can be changed in the short run.

• Marginal Product: Additional output from one more unit of input. $MP = \frac{\Delta Q}{\Delta L}$

• Specialization: Focusing on a narrow set of tasks to increase productivity.

• Law of Diminishing Returns: As more of a variable input is added, marginal product eventually decreases.

• Cost of Production: Total expenses incurred in producing goods.

• Total Cost: Sum of fixed and variable costs. $TC = FC + VC$

• Variable Cost: Costs that change with output.

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

• Average Total Cost: $ATC = \frac{TC}{Q}$

• Average Variable Cost: $AVC = \frac{VC}{Q}$

• Average Fixed Cost: $AFC = \frac{FC}{Q}$

• Marginal Cost: $MC = \frac{\Delta TC}{\Delta Q}$

• Revenue: Income from sales. $TR = P \times Q$

• Marginal Revenue: Additional revenue from selling one more unit. $MR = \frac{\Delta TR}{\Delta Q}$

• Profits: Difference between total revenue and total cost. $\text{Profit} = TR - TC$

• Accounting Profits: $\text{Accounting Profit} = TR - \text{Explicit Costs}$

• Economic Profits: $\text{Economic Profit} = TR - (\text{Explicit Costs} + \text{Implicit Costs})$

• Price Elasticity of Supply: Measures responsiveness of quantity supplied to price changes. $\varepsilon_s = \frac{\%\,\text{change in } Q_s}{\%\,\text{change in } P}$

• Producer Surplus: Difference between price received and minimum price willing to accept.

• Economies of Scale: Average cost decreases as output increases.

• Constant Returns to Scale: Average cost remains unchanged as output increases.

• Diseconomies of Scale: Average cost increases as output increases.

• Free Entry: Firms can enter the market without restrictions.

• Free Exit: Firms can leave the market without restrictions.

Example: A bakery experiences economies of scale as it produces more bread, lowering average costs.

Summary Table: Types of Elasticity

Type	Formula	Interpretation
Price Elasticity of Demand	$\varepsilon_d = \frac{\%\,\text{change in } Q_d}{\%\,\text{change in } P}$	Responsiveness of demand to price changes
Cross-Price Elasticity	$\varepsilon_{xy} = \frac{\%\,\text{change in } Q_x}{\%\,\text{change in } P_y}$	Effect of price change in one good on demand for another
Income Elasticity	$\varepsilon_I = \frac{\%\,\text{change in } Q}{\%\,\text{change in } I}$	Effect of income change on demand
Price Elasticity of Supply	$\varepsilon_s = \frac{\%\,\text{change in } Q_s}{\%\,\text{change in } P}$	Responsiveness of supply to price changes

Additional info: Academic context and formulas have been expanded for clarity and completeness.