How economists approach the world
IB Economics SLΒ· 15 min read
1. Positive vs Normative Economicsβ βββββ± 4 min
Positive vs Normative Economics
Positive economics focuses on objective, testable claims about how the economy functions. Normative economics focuses on subjective, value-based claims about what economic policy or outcomes should be.
Example:
Positive: 'A 10% minimum wage increase raises youth unemployment by 2%' (testable with data). Normative: 'Governments should raise the minimum wage' (value judgment).
Classify each statement as positive or normative: (1) Higher carbon taxes reduce greenhouse gas emissions. (2) Governments should prioritise reducing income inequality. (3) A 5% increase in consumer spending raises real GDP by 3%.
- 1
Recall the core distinction: positive = testable, normative = value-based judgment often containing 'should'.
- 2
Evaluate statement 1: This claim can be verified or rejected with real-world data on taxes and emissions, so it is positive.
- 3
Evaluate statement 2: This is a policy recommendation rooted in values, it cannot be proven true or false, so it is normative.
- 4
Evaluate statement 3: This claim can be tested against national income data, so it is positive.
2. The Ceteris Paribus Assumptionβ β ββββ± 5 min
Ceteris Paribus
A core methodological assumption meaning 'all other things being equal'. Economists use this to isolate the effect of one variable on an outcome, since the real world has many overlapping changing factors.
A student argues: 'The law of demand says higher prices reduce quantity bought. Coffee prices rose last year, and I bought more coffee, so the law of demand is wrong'. Use ceteris paribus to explain the student's error.
- 1
Recall that the law of demand only applies when all other factors that affect demand (income, preferences, prices of other goods) are held constant (ceteris paribus).
- 2
Identify that other factors likely changed for the student: for example, their income may have increased, or their preference for coffee grew, or a local coffee shop closed.
- 3
The student violated the ceteris paribus assumption by allowing other factors to change. The law of demand does not claim higher prices always lead to lower quantity bought regardless of other changes, so the student's observation does not disprove the law.
3. The Role of Economic Modelsβ β ββββ± 4 min
Economists rarely can run large-scale controlled experiments to test theories, so they rely on models: simplified representations of the real world that cut through irrelevant detail to focus on core relationships.
Economic Model
A simplified, abstract representation of economic behaviour or markets, used to explain outcomes and make predictions. Models can be graphical, mathematical, or verbal.
Example:
The production possibilities curve (PPC) is a simple model that illustrates scarcity and trade-offs for an economy producing two goods.
Critics say economic models are useless because they are not perfectly realistic. Is this a valid criticism?
- 1
The goal of an economic model is not to perfectly replicate the entire real world, which would be so complex it would be impossible to interpret or use.
- 2
By leaving out non-essential details, models let economists focus on the specific relationship they are studying, for example how price affects quantity demanded.
- 3
Simplification is not a weakness of economic models: it is a necessary feature of useful analysis. A model that included every detail would be as complex as the real world itself and useless for prediction.
4. Microeconomics vs Macroeconomicsβ βββββ± 3 min
Microeconomics vs Macroeconomics
Microeconomics studies the behaviour of individual decision-making units: households, firms, and individual markets. Macroeconomics studies the economy as a whole, focusing on aggregate outcomes like national unemployment, inflation, and economic growth.
Classify each topic as microeconomic or macroeconomic: (1) The effect of rent control on the Paris housing market. (2) The impact of interest rate hikes on national inflation.
- 1
Recall the core split: microeconomics = individual agents or single markets, macroeconomics = whole economy aggregate outcomes.
- 2
Topic 1 focuses on one individual market (housing in Paris), so it is microeconomics.
- 3
Topic 2 focuses on national inflation, an aggregate outcome for the entire economy, so it is macroeconomics.
5. Common Pitfalls
Wrong move:
Claiming normative economics is useless because it is subjective.
Why:
Normative values drive all policy debates, and all policy decisions combine positive analysis and normative judgments.
Correct move:
Recognise that both positive and normative analysis are core to economics, just with different purposes.
Wrong move:
Interpreting ceteris paribus as a claim that no other variables ever change in the real world.
Why:
Ceteris paribus is an analytical assumption, not a description of real-world conditions.
Correct move:
Understand ceteris paribus is used to isolate the effect of one variable for analysis, it does not claim other variables never change.
Wrong move:
Claiming economic models are invalid because they are simplified and not perfectly realistic.
Why:
All models across all sciences simplify reality to answer specific questions.
Correct move:
Evaluate models based on whether they produce useful predictions for the question being studied, not perfect realism.
Wrong move:
Classifying any topic involving government as macroeconomics.
Why:
Government intervention in individual markets is a microeconomic topic, not macro.
Correct move:
Classify based on level of analysis: individual market = micro, whole economy aggregate outcome = macro.
6. Quick Reference Cheatsheet
Term | Core Definition |
|---|---|
Positive economics | Testable, objective claim about economic reality |
Normative economics | Value-based, non-testable claim about what should be |
Ceteris paribus | All other things held equal, isolates one variable's effect |
Economic model | Simplified representation of reality for analysis |
Microeconomics | Studies individual agents and single markets |
Macroeconomics | Studies the aggregate economy as a whole |
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.
- 2022 Β· 1
Classify positive vs normative statement
- 2019 Β· 1
Explain the ceteris paribus assumption
What's Next
This foundational methodology underpins every topic you will study in IB Economics SL, from supply and demand to macroeconomic policy. The distinctions you learned here will help you identify different types of claims in exam questions and structure your own answers correctly, especially when evaluating policy where both positive and normative perspectives matter. Next, you will apply these core ideas to the first core economic model: the production possibilities curve, which illustrates the fundamental problem of scarcity and trade-offs, and build on these distinctions for all future topics.
- βDemand
- βMicroeconomics
- βSupply