Microeconomics: Foundations, Markets, and Elasticity – Study Notes

Chapter 1: Economics – Foundations and Models

Introduction to Economics

• Economy: A system that produces goods and services and distributes them to people.

• Two main types of economies:

  • Market Economy: Individuals and businesses make decisions about production, buying, and selling.

  • Command Economy: A central authority or government makes major economic decisions.

Microeconomics vs. Macroeconomics

• Microeconomics: Studies how individuals and businesses make decisions and interact in markets.

• Macroeconomics: Studies the economy as a whole, including aggregate measures like GDP and unemployment.

Basic Economic Concepts

• Individual Choice: Decisions people make about how to use their limited resources.

• Scarcity: The fundamental economic problem; resources are limited relative to wants and needs.

• Four Types of Resources:

  • Land: Natural resources used in production.

  • Labor: Human effort used in production.

  • Capital: Man-made resources (e.g., machines, buildings) used to produce goods and services.

  • Human Capital: The knowledge, skills, and experience possessed by individuals.

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

• Trade-Off: Comparing the costs and benefits of different actions.

• Decision at the Margin: Deciding whether to do a little more or less of something by comparing additional costs and benefits.

Specialization and Trade

• Specialization: Focusing on tasks one is best at performing, increasing efficiency.

• Trade: The exchange of goods or services, which can make both parties better off.

• Gains from Trade: The benefits that arise from trading with others.

Efficiency, Equity, and Market Failure

• Efficiency: Using resources so that it is impossible to make someone better off without making someone else worse off (Pareto efficiency).

• Equity: Fairness in the distribution of resources, goods, or benefits.

• Market Failure: When the market does not allocate resources efficiently on its own.

• Economy-Wide Interaction: Economic decisions by individuals affect others in the economy.

Economic Fluctuations

• Recession: A period of declining economic activity, leading to lower spending, income, layoffs, and higher unemployment.

Chapter 2: Trade-Offs, Comparative Advantage, and the Market System

Market Structures

• Perfectly Competitive Market: Many buyers and sellers, identical products, no single buyer or seller can influence the price.

Demand

• Demand: The willingness and ability of consumers to buy a product.

• Demand Curve: Graph showing the relationship between price and quantity demanded (downward sloping).

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

• Quantity Demanded: The amount consumers are willing and able to buy at a specific price.

• Ceteris Paribus: Latin for "all other things being equal"; used to isolate the effect of one variable.

• Law of Demand: When price increases, quantity demanded decreases; when price decreases, quantity demanded increases.

Shifts and Movements in Demand and Supply

• Movement along the curve: Caused by a change in price.

• Shift of the curve: Caused by changes in other factors (e.g., income, tastes, prices of related goods).

Types of Goods

• Normal Good: Demand increases as income increases.

• Inferior Good: Demand decreases as income increases.

• Substitutes: Goods that can replace each other; if the price of one falls, demand for the other falls.

• Complements: Goods used together; if the price of one falls, demand for the other increases.

Supply

• Supply: The willingness and ability of producers to sell a product.

• Supply Curve: Graph showing the relationship between price and quantity supplied (upward sloping).

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

• Quantity Supplied: The amount producers are willing and able to sell at a particular price.

• Law of Supply: When price increases, quantity supplied increases; when price decreases, quantity supplied decreases.

Market Equilibrium

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

• Equilibrium Price: The price at which QD = QS.

• Equilibrium Quantity: The quantity bought and sold at the equilibrium price.

• Competitive Market Equilibrium: Equilibrium in a market with many buyers and sellers.

• Shortage: Quantity demanded exceeds quantity supplied (QD > QS).

• Surplus: Quantity supplied exceeds quantity demanded (QS > QD).

Chapter 3: Where Prices Come From – The Interaction of Demand and Supply

Consumer Surplus

• Consumer Surplus: The difference between what a consumer is willing to pay and what they actually pay; represents the benefit to buyers.

• Willingness to Pay: The maximum price a consumer is willing to pay for a good or service.

• Formula:

  • $Consumer\ Surplus = \frac{1}{2} \times Quantity \times (Maximum\ Price - Market\ Price)$

• On a graph: Area below the demand curve and above the market price.

• To find new consumer surplus after a price change:

  • $New\ CS = \frac{1}{2} \times Quantity\ Demanded \times (Max\ Price - New\ Price)$

Producer Surplus

• Producer Surplus: The difference between the lowest price a producer is willing to accept and the price they actually receive; represents the benefit to sellers.

• Formula:

  • $Producer\ Surplus = \frac{1}{2} \times (Market\ Price - Minimum\ Price)$ (when area is a triangle)

• On a graph: Area above the supply curve and below the market price.

• To find new producer surplus after a price change:

  • $New\ PS = \frac{1}{2} \times Quantity\ Supplied \times (New\ Price - Min\ Price)$

• Producer and consumer surplus can be calculated as the sum of a rectangle and a triangle:

  • Rectangle: $Q \times (New\ Price - Old/Equilibrium\ Price)$

  • Triangle: $\frac{1}{2} \times Q \times (Old/Equilibrium\ Price - Minimum\ Price)$

Economic Surplus (Total Surplus)

• Economic Surplus: The total benefit to buyers and sellers from market transactions.

• Formula:

  • $Total\ Surplus = Consumer\ Surplus + Producer\ Surplus$

Marginal Analysis

• Marginal Benefit: The additional benefit from consuming one more unit of a good or service.

• Marginal Cost: The additional cost of producing one more unit of a good or service.

Government Intervention

• Price Floor: A legally established minimum price that sellers can receive for a good or service (e.g., minimum wage).

• Price Ceiling: A legally established maximum price that sellers can charge for a good or service (e.g., rent control).

Measuring Prices

• Consumer Price Index (CPI): A measure of the average prices of goods and services purchased by a typical consumer; used to track inflation.

Chapter 4: Elasticity – The Responsiveness of Demand and Supply

Price Elasticity of Demand (PED)

• Elasticity: Measures how responsive quantity demanded or supplied is to a change in price.

• Formula:

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

  • $\%\ change\ in\ quantity\ demanded = \frac{(New\ Q - Old\ Q)}{Old\ Q} \times 100$

  • $\%\ change\ in\ price = \frac{(New\ P - Old\ P)}{Old\ P} \times 100$

• Interpretation:

  • Elastic (PED > 1): Quantity demanded is very responsive to price changes (flatter demand curve).

  • Inelastic (PED < 1): Quantity demanded is not very responsive to price changes (steeper demand curve).

  • Unit Elastic (PED = 1): Percentage change in quantity demanded equals percentage change in price.

  • Perfectly Inelastic (PED = 0): Vertical demand curve; quantity demanded does not change when price changes.

  • Perfectly Elastic (PED = ∞): Horizontal demand curve; quantity demanded changes infinitely with any price change.

Total Revenue and Elasticity

• Total Revenue (TR): The amount a seller receives from sales.

• Formula:

  • $TR = Price \times Quantity\ Sold$

• Elasticity affects how total revenue changes with price:

  • If demand is elastic, lowering price increases total revenue.

  • If demand is inelastic, raising price increases total revenue.

Midpoint Formula for PED

• Midpoint Formula: Used to calculate elasticity between two points.

• Formula:

  • $PED = \frac{(Q_2 - Q_1) / ((Q_2 + Q_1)/2)}{(P_2 - P_1) / ((P_2 + P_1)/2)}$

Cross-Price Elasticity of Demand

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

• Formula:

  • $Cross\text{-}Price\ Elasticity = \frac{\%\ change\ in\ quantity\ demanded\ of\ A}{\%\ change\ in\ price\ of\ B}$

• Positive value: Goods are substitutes. Negative value: Goods are complements.

Price Elasticity of Supply (PES)

• Price Elasticity of Supply: Measures how responsive quantity supplied is to a change in price.

• Formula:

  • $PES = \frac{\%\ change\ in\ quantity\ supplied}{\%\ change\ in\ price}$

Example Table: Types of Elasticity

Type	PED Value	Demand Curve Shape	Interpretation
Perfectly Inelastic	0	Vertical	Quantity demanded does not change with price
Inelastic	< 1	Steep	Quantity demanded changes less than price
Unit Elastic	= 1	Intermediate	Quantity demanded changes exactly as price
Elastic	> 1	Flat	Quantity demanded changes more than price
Perfectly Elastic	∞	Horizontal	Any price change causes infinite change in quantity demanded