Microeconomics: Core Concepts and Foundations (Chapters 1–5 Study Notes)

Economic Issues and Concepts

Scarcity, Choice, and Opportunity Cost

Economics studies how societies allocate scarce resources to satisfy unlimited wants. Scarcity forces individuals and societies to make choices, leading to the concept of opportunity cost.

• Scarcity: The fundamental economic problem of having limited resources to meet unlimited wants.

• Choice: The act of selecting among alternatives due to scarcity.

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

• Resource Allocation: The process of assigning scarce resources to various uses.

• Factors of Production: Resources used to produce goods and services, typically categorized as land, labour, and capital.

Example: If a government spends money on healthcare, the opportunity cost may be less spending on education.

Production Possibilities Boundary (PPB)

The PPB illustrates the maximum attainable combinations of two goods that can be produced with available resources and technology, assuming efficient use.

• PPB Curve: Shows the trade-offs between two goods; points inside are inefficient, points on are efficient, and points outside are unattainable.

• Marginal Decisions: Choices made by comparing the additional benefit and cost of an action.

Equation:

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

Specialization, Division of Labour, and Trade

Specialization and division of labour increase productivity by allowing individuals to focus on specific tasks. Trade enables individuals and nations to obtain goods and services they do not produce themselves.

• Specialization: Concentrating on a narrow range of tasks to increase efficiency.

• Division of Labour: Breaking up production into specialized tasks performed by different workers.

• Barter: Direct exchange of goods and services without money.

• Money: Facilitates trade by serving as a medium of exchange.

Example: In a car factory, one worker assembles engines while another paints the car body.

Types of Economic Systems

Economic systems differ in how they allocate resources and make decisions.

• Traditional Economy: Decisions based on customs and traditions.

• Command Economy: Central authority makes most economic decisions.

• Free-Market Economy: Private households and firms make most decisions.

• Mixed Economy: Both government and private sector play roles in decision-making.

Economic Theories, Data, and Graphs

Positive and Normative Statements

Economists distinguish between statements of fact and statements of value.

• Positive Statement: Describes what is, was, or will be; fact-based and testable.

• Normative Statement: Describes what ought to be; based on value judgments.

Example: "Raising the minimum wage increases unemployment" (positive). "The government should raise the minimum wage" (normative).

Theories, Models, and Variables

Economic theories use models to explain and predict relationships between variables.

• Variable: Any item that can take on different values (e.g., price, quantity).

• Endogenous Variable: Explained within the model (dependent variable).

• Exogenous Variable: Determined outside the model (independent variable).

• Assumptions: Simplifications made to focus on key relationships.

• Predictions: Outcomes derived from the model.

Data Types and Graphical Analysis

• Cross-Sectional Data: Observations at a single point in time across different units.

• Time-Series Data: Observations over time for a single unit.

• Scatter Diagram: Graph showing the relationship between two variables.

• Index Number: Measures a variable relative to a base period (base = 100).

Correlation vs. Causation

Correlation indicates a relationship between variables, but does not imply one causes the other.

• Positive Relation: Both variables move in the same direction.

• Negative Relation: Variables move in opposite directions.

Demand, Supply, and Price

Stock and Flow Variables

• Stock Variable: Measured at a point in time (e.g., wealth).

• Flow Variable: Measured over a period of time (e.g., income).

Demand and Supply

Markets are governed by the forces of demand and supply, determining prices and quantities.

• Quantity Demanded: Amount consumers want to buy at a given price.

• Demand Curve: Shows the relationship between price and quantity demanded, ceteris paribus.

• Change in Quantity Demanded: Movement along the demand curve due to price change.

• Change in Demand: Shift of the demand curve due to factors other than price (e.g., income, tastes).

• Quantity Supplied: Amount producers want to sell at a given price.

• Supply Curve: Shows the relationship between price and quantity supplied.

• Change in Quantity Supplied: Movement along the supply curve due to price change.

• Change in Supply: Shift of the supply curve due to factors other than price (e.g., technology, input prices).

Market Equilibrium and Disequilibrium

• Equilibrium Price: Price at which quantity demanded equals quantity supplied.

• Disequilibrium: Occurs when there is excess demand (shortage) or excess supply (surplus).

• Comparative Statics: Analysis of how changes in exogenous variables affect equilibrium.

Equation:

$Q_d = Q_s$ (at equilibrium)

Relative and Absolute Prices

• Absolute Price: The money price of a good.

• Relative Price: The price of one good in terms of another.

Equation:

$Relative\ Price = \frac{Price\ of\ Good\ A}{Price\ of\ Good\ B}$

Substitutes and Complements

• Substitutes in Consumption: Goods that can replace each other (e.g., tea and coffee).

• Complements in Consumption: Goods consumed together (e.g., printers and ink cartridges).

Elasticity

Price Elasticity of Demand

Measures the responsiveness of quantity demanded to a change in price.

• Formula:

$\eta = \frac{\%\ Change\ in\ Quantity\ Demanded}{\%\ Change\ in\ Price}$

• Inelastic Demand: Elasticity less than 1; quantity demanded changes less than price.

• Elastic Demand: Elasticity greater than 1; quantity demanded changes more than price.

• Perfectly Inelastic: Elasticity is 0; quantity demanded does not change with price.

• Perfectly Elastic: Elasticity is infinite; quantity demanded drops to zero with any price increase.

Price Elasticity of Supply

• Formula:

$\eta_s = \frac{\%\ Change\ in\ Quantity\ Supplied}{\%\ Change\ in\ Price}$

Income Elasticity of Demand

• Formula:

$\eta_Y = \frac{\%\ Change\ in\ Quantity\ Demanded}{\%\ Change\ in\ Income}$

• Normal Good: Positive income elasticity; demand rises as income rises.

• Inferior Good: Negative income elasticity; demand falls as income rises.

• Necessities: Income elasticity between 0 and 1.

• Luxuries: Income elasticity greater than 1.

Cross Elasticity of Demand

• Formula:

$\eta_{xy} = \frac{\%\ Change\ in\ Quantity\ Demanded\ of\ Good\ X}{\%\ Change\ in\ Price\ of\ Good\ Y}$

• Substitutes: Positive cross elasticity.

• Complements: Negative cross elasticity.

Elasticity and Total Expenditure

• If demand is elastic, a price decrease increases total expenditure.

• If demand is inelastic, a price decrease decreases total expenditure.

Tax Incidence and Excise Taxes

• Excise Tax: Tax on the sale of a specific product.

• Tax Incidence: The division of the tax burden between buyers and sellers, depending on relative elasticities.

Price Controls and Market Efficiency

Price Ceilings and Floors

• Price Ceiling: Legal maximum price; can cause shortages if set below equilibrium.

• Price Floor: Legal minimum price; can cause surpluses if set above equilibrium.

Consequences of Price Controls

• Black Markets: Illegal markets that arise when price controls make legal markets unprofitable.

• Allocation by Sellers' Preferences: Sellers choose who receives goods in shortage situations.

• Rent Controls: Price ceilings on rental housing, often leading to shortages and reduced quality.

Market Efficiency and Surplus

• Economic Surplus: The sum of consumer and producer surplus; maximized at equilibrium.

• Market Efficiency: Achieved when resources are allocated to maximize total surplus.

• Inefficiency of Price Controls: Price controls and output quotas reduce total surplus and create deadweight loss.

Short-Run and Long-Run Supply Responses

• Supply is typically more elastic in the long run than in the short run, affecting the impact of price controls over time.

Table: Types of Economic Systems

System	Decision Maker	Resource Allocation
Traditional	Customs/Tradition	Based on historical precedent
Command	Central Authority	Government plans
Free-Market	Households/Firms	Market forces
Mixed	Households, Firms, Government	Combination of market and government

Table: Types of Elasticity

Elasticity Type	Formula	Interpretation
Price Elasticity of Demand	$\eta = \frac{\%\ Change\ in\ Q_d}{\%\ Change\ in\ P}$	Responsiveness of demand to price changes
Price Elasticity of Supply	$\eta_s = \frac{\%\ Change\ in\ Q_s}{\%\ Change\ in\ P}$	Responsiveness of supply to price changes
Income Elasticity of Demand	$\eta_Y = \frac{\%\ Change\ in\ Q_d}{\%\ Change\ in\ Y}$	Responsiveness of demand to income changes
Cross Elasticity of Demand	$\eta_{xy} = \frac{\%\ Change\ in\ Q_{dx}}{\%\ Change\ in\ P_y}$	Responsiveness of demand for one good to price changes in another

Additional info: Some explanations and examples have been expanded for clarity and completeness, as the original notes were in point form.