Foundations of Microeconomics: Core Concepts and Principles

Economics: Basic Concepts

Definition of Economics

Economics is the study of how individuals, firms, and societies allocate scarce resources to satisfy unlimited wants. It examines the choices made under conditions of scarcity and the consequences of those choices.

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

• Efficiency: Achieving the maximum output from given resources.

Main Ideas of Economics

• Marginalism: The analysis of decisions based on marginal (additional) changes in resources or benefits.

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

• Tradeoffs: The necessity to give up one thing to obtain another due to scarcity.

• Incentives: Factors that motivate individuals and firms to make decisions in their best interest.

• Rationalism: The assumption that individuals make decisions to maximize their utility or benefit.

Three Economic Questions

Every economy must answer three basic questions:

1. What to produce?

2. How to produce?

3. For whom to produce?

Scientific Method in Economics

Economists use the scientific method to develop models and test hypotheses about economic behavior.

• Positive Statements: Objective statements that can be tested and validated ("what is").

• Normative Statements: Subjective statements based on opinions or values ("what ought to be").

Economic Systems

Economic systems determine how resources are allocated and include:

• Market Economy: Decisions are made by individuals and firms interacting in markets.

• Command Economy: The government makes most economic decisions.

• Mixed Economy: Combines elements of both market and command economies.

Factors of Production

The resources used to produce goods and services:

• Land: Natural resources

• Labor: Human effort

• Capital: Manufactured goods used in production

• Entrepreneurship: The ability to organize resources and take risks

Production Possibilities

Production Possibilities Frontier (PPF)

The PPF is a graph that shows the maximum combinations of two goods that can be produced with available resources and technology.

• Opportunity Cost and Slope: The slope of the PPF represents the opportunity cost of one good in terms of the other.

• Growth: Outward shifts in the PPF indicate economic growth.

• Shape: Increasing Opportunity Cost: The PPF is typically bowed outward due to increasing opportunity costs as resources are specialized.

Trade and the PPF

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

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

• Specialization: Focusing on the production of goods for which one has a comparative advantage.

• Terms of Trade: The rate at which goods are exchanged between countries or individuals.

Property Rights and Contract Enforcement

Well-defined property rights and contract enforcement are essential for efficient market functioning, as they provide incentives for investment and trade.

Demand and Supply

Demand

Demand refers to the quantity of a good or service that consumers are willing and able to purchase at various prices.

• Law of Demand: As the price of a good increases, the quantity demanded decreases, ceteris paribus.

• Graph: The demand curve slopes downward from left to right.

• Quantity Demanded vs. Demand: Quantity demanded is a specific point on the demand curve; demand refers to the entire curve.

• Shift of Demand vs. Movement Along Demand: A change in price causes movement along the curve; other factors (income, tastes, prices of related goods) shift the curve.

• Market Demand: The sum of all individual demands in a market.

• Demand Shifters: Income, tastes, prices of substitutes/complements, expectations, number of buyers.

Supply

Supply is the quantity of a good or service that producers are willing and able to sell at various prices.

• Law of Supply: As the price of a good increases, the quantity supplied increases, ceteris paribus.

• Graph: The supply curve slopes upward from left to right.

• Quantity Supplied vs. Supply: Quantity supplied is a specific point on the supply curve; supply refers to the entire curve.

• Shift of Supply vs. Movement Along Supply: A change in price causes movement along the curve; other factors (input prices, technology, expectations, number of sellers) shift the curve.

• Market Supply: The sum of all individual supplies in a market.

Equilibrium

Market equilibrium occurs where quantity demanded equals quantity supplied.

• Shortages: Occur when quantity demanded exceeds quantity supplied at a given price.

• Surpluses: Occur when quantity supplied exceeds quantity demanded at a given price.

Shifts and the Equilibrium

• Simultaneous Shifts: When both demand and supply curves shift, the effect on equilibrium price and quantity depends on the direction and magnitude of each shift.

Elasticity

Price Elasticity of Demand

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

• Formula:

$E_d = \frac{\%\ \text{change in quantity demanded}}{\%\ \text{change in price}}$

• Calculation: Use the midpoint formula for accuracy:

$E_d = \frac{(Q_2 - Q_1)/[(Q_2 + Q_1)/2]}{(P_2 - P_1)/[(P_2 + P_1)/2]}$

• Elasticity and Total Revenue: If demand is elastic ($E_d > 1$), a price decrease increases total revenue; if inelastic ($E_d < 1$), a price decrease decreases total revenue.

• Along a Linear Demand: Elasticity varies along a straight-line demand curve, being more elastic at higher prices and less elastic at lower prices.

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

• Applications: Pricing strategies, tax incidence, and policy analysis.

Income Elasticity of Demand

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

• Formula:

$E_y = \frac{\%\ \text{change in quantity demanded}}{\%\ \text{change in income}}$

• Range: Inferior goods ($E_y < 0$), normal goods ($E_y > 0$), necessities ($0 < E_y < 1$), luxuries ($E_y > 1$).

Cross-Price Elasticity of Demand

Measures the responsiveness of quantity demanded for one good to a change in the price of another good.

• Formula:

$E_{xy} = \frac{\%\ \text{change in quantity demanded of good X}}{\%\ \text{change in price of good Y}}$

• Range: Complements ($E_{xy} < 0$), substitutes ($E_{xy} > 0$).

Example Table: Types of Elasticity

Elasticity Type	Formula	Interpretation
Price Elasticity of Demand	$E_d = \frac{\%\ \text{change in Qd}}{\%\ \text{change in P}}$	Measures sensitivity of Qd to price changes
Income Elasticity of Demand	$E_y = \frac{\%\ \text{change in Qd}}{\%\ \text{change in Y}}$	Measures sensitivity of Qd to income changes
Cross-Price Elasticity of Demand	$E_{xy} = \frac{\%\ \text{change in Qd of X}}{\%\ \text{change in P of Y}}$	Measures sensitivity of Qd for X to price changes in Y

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