Introduction to Economics – Study Notes
1. What Is Economics?
| Aspect |
Definition |
| Broad meaning |
The social science that examines how societies allocate scarce resources to satisfy unlimited wants. |
| Core question |
What to produce? — How to produce? — For whom to produce? |
| Key concepts |
Scarcity, choice, opportunity cost, trade‑offs, incentives. |
2. Branches of Economics
| Branch |
Focus |
Typical Topics |
| Microeconomics |
Behavior of individual agents (households, firms, markets). |
Supply & demand, consumer theory, production theory, market structures, welfare analysis. |
| Macroeconomics |
Aggregate economy-wide phenomena. |
GDP, inflation, unemployment, fiscal & monetary policy, economic growth, international trade. |
| Other sub‑fields |
Behavioral, development, environmental, health, industrial organization, public finance, etc. |
|
3. Fundamental Economic Principles
| Principle |
Explanation |
Example |
| Scarcity |
Resources (land, labor, capital, entrepreneurship) are limited relative to wants. |
A country cannot produce infinite cars because it has limited factories and workers. |
| Opportunity Cost |
The value of the best alternative foregone when a decision is made. |
Choosing to study economics instead of engineering costs the future engineering salary you could have earned. |
| Marginal Analysis |
Decisions are made by comparing additional (marginal) benefits and costs. |
A bakery bakes a 101st loaf only if the extra profit exceeds the extra cost of ingredients and labor. |
| Incentives |
People respond to changes in costs and benefits. |
A tax on cigarettes raises the price, reducing consumption. |
| Trade‑offs |
Achieving one goal often requires sacrificing another. |
Higher economic growth may increase pollution unless mitigated. |
| Efficiency vs. Equity |
Efficiency: maximizing total output. Equity: fair distribution of resources. |
Free‑market outcomes can be efficient but may require redistribution for equity. |
4. The Economic Model: The Circular Flow
Households
↓ ↑
(Factors of Production) (Goods & Services)
↔ ↔
Firms
- Households supply labor, land, and capital to firms and receive wages, rent, interest, and profit.
- Firms use these factors to produce goods/services, which they sell to households.
- The model can be expanded to include government (taxes, spending), foreign sector (exports/imports), and financial markets (savings & investment).
5. The Economic Way of Thinking
- Start with a question – e.g., “Why do prices rise?”
- Build a simple model – identify agents, constraints, and objectives.
- Derive predictions – use logic or mathematics to see what the model implies.
- Test against data – compare predictions with real‑world observations.
- Refine the model – add realism (e.g., imperfect information) if needed.
6. Key Economic Variables
| Variable |
Symbol |
What It Measures |
| Gross Domestic Product (GDP) |
(Y) or (GDP) |
Total market value of final goods & services produced in a period. |
| Price Level |
(P) |
Average price of a basket of goods (e |