What is economics
IB Economics SLΒ· Unit 1: Introduction to Economics, Section 1.1Β· 10 min read
1. The Core Economic Problem: Scarcityβ βββββ± 3 min
Scarcity
The universal, permanent condition where society has unlimited wants, but only a limited amount of resources (factors of production) to satisfy those wants.
Example:
A city has 100 hectares of empty land; it can build a new public park or a new housing development, but cannot do both at full capacity because land is a scarce resource.
Scarcity applies to all economic agents: individual consumers, firms, and governments. Even the wealthiest person on Earth has limited time and unlimited wants, so they still face scarcity and must make choices.
A student has 2 hours of free time on a Friday evening. They can either go to the movies with friends or study for a Monday math test. Explain why scarcity applies to this scenario.
- 1
- Identify the limited resource: the student only has 2 hours of free time available, which is finite.
- 2
- Identify the unlimited wants: the student wants both to socialize at the movies and to get a good grade by studying.
- 3
- Because the limited resource of time cannot satisfy both wants fully, the condition of scarcity holds.
2. Scarcity, Choice and Opportunity Costβ βββββ± 4 min
Because scarcity means we cannot have everything we want, we must make choices between competing alternatives. Every choice means giving up something else, and the value of the next best alternative we give up is called opportunity cost.
Opportunity Cost
The value of the next highest-valued alternative that is foregone when a choice is made. Only the next best alternative counts, not all possible alternatives.
Example:
If you rank your options for a Saturday as: 1) work for extbackslashackslash$100, 2) go to a concert, 3) stay home, the opportunity cost of working is the value of going to the concert.
A local government has a extbackslashackslash5 million grant that can only fund one infrastructure project. The top two options are: a new bike lane network (valued at extbackslashackslash5 million benefit) or a new sewage treatment plant (valued at extbackslashackslash$4 million benefit). What is the opportunity cost of building the bike lanes?
- 1
- Identify the choice made: the government uses all extbackslashackslash$5 million to build the bike lane network.
- 2
- Identify the next best alternative: the sewage treatment plant, which provides extbackslashackslash$4 million of benefit to the community.
- 3
- Opportunity cost is the value of the next best alternative foregone, so the opportunity cost is the sewage treatment plant and its extbackslashackslash$4 million of benefit.
Test your understanding:
What is the opportunity cost of attending university full-time?
A. Only the tuition fees you pay to attend
B. The full-time job you would have taken if you did not attend
C. There is no opportunity cost if your parents pay your tuition
D. Only the cost of textbooks and accommodation
Reveal answer
B βOpportunity cost counts the next best alternative, not just monetary costs. The highest-valued alternative to full-time university is almost always a full-time job, whose wages and experience are the opportunity cost of your choice.
3. Core Branches: Microeconomics vs Macroeconomicsβ βββββ± 3 min
IB Economics divides the discipline into two broad branches based on the scope of the question being studied: microeconomics focuses on small-scale individual decision-making, while macroeconomics focuses on the economy as a whole.
Branches of Economics
The core split of economics based on scope: microeconomics studies individual agents and markets, while macroeconomics studies the aggregate economy.
- Microeconomics: Topics include consumer behavior, firm pricing, individual market supply and demand, international trade, and market failure.
- Macroeconomics: Topics include inflation, unemployment, economic growth, fiscal and monetary policy, and global economic development.
Classify each question as microeconomics or macroeconomics: (1) How will a tax on sugary drinks affect soda sales? (2) How will a national sales tax affect the overall unemployment rate?
- 1
- For question 1, the question focuses on the specific market for sodas, an individual market. This is a microeconomics question.
- 2
- For question 2, the question asks about the overall unemployment rate of the entire national economy. This is a macroeconomics question.
4. Common Pitfalls
Wrong move:
Claiming opportunity cost is the sum of all alternatives you give up.
Why:
Opportunity cost only counts the next best (highest-valued) alternative, not every possible alternative you did not choose.
Correct move:
Only include the value of the single highest-valued option you did not choose when calculating opportunity cost.
Wrong move:
Confusing scarcity with a temporary shortage of a good.
Why:
A shortage is a temporary condition where demand exceeds supply at the current price. Scarcity is a permanent, universal condition of limited resources vs unlimited wants.
Correct move:
Remember that scarcity exists even if there is no shortage of any specific good in the market.
Wrong move:
Claiming that rich people do not face scarcity.
Why:
Even billionaires have limited time and unlimited wants, so they still must make choices between competing options.
Correct move:
Scarcity applies to all people and societies, regardless of their total income or accumulated wealth.
Wrong move:
Thinking opportunity cost is only measured in money.
Why:
Opportunity cost measures value, which often includes non-monetary benefits like time, experience, or enjoyment.
Correct move:
Always consider non-monetary alternatives when identifying opportunity cost in exam questions.
5. Quick Reference Cheatsheet
Concept | Core Definition |
|---|---|
Scarcity | Unlimited wants exceed limited resources, core economic problem |
Choice | Required due to scarcity; every choice involves trade-offs |
Opportunity Cost | Value of the next best alternative foregone |
Microeconomics | Study of individual agents and specific markets |
Macroeconomics | Study of the aggregate economy as a whole |
6. Frequently Asked
Why is economics called the 'study of scarcity'?
All economic analysis originates from the core problem that unlimited wants exceed limited resources. Every economic concept, from supply and demand to government policy, is designed to address the consequences of scarcity, so the discipline is fundamentally rooted in this problem.
When this came up on past exams
AI-estimated based on syllabus patterns β cross-check with official past papers for accuracy. Use only as revision-focus signals.
- 2025 Β· 1
1 marker on opportunity cost definition
- 2024 Β· 1
Identify definition of scarcity
- 2023 Β· 2
Linked to PPF opportunity cost question
Going deeper
What's Next
The concepts of scarcity, choice and opportunity cost you learned here are the foundation for every other topic you will study in IB Economics SL. All economic analysis, from supply and demand to fiscal policy, starts from the core assumption that scarcity forces trade-offs between competing options. Next, you will build on these concepts to study factors of production and the production possibilities frontier (PPF), a graphical model that illustrates opportunity cost and trade-offs for an economy. Mastering these basic concepts now will make all more advanced topics much easier to understand, as you will recognize the core logic that ties all of economics together.