Positive vs normative statement?

Positive: factual, testable with evidence. Normative: contains a value judgement about what ought to be.

What does ceteris paribus mean?

"All other things being equal": other variables are held constant to isolate the effect of one change.

Why do economists use models?

To simplify a complex reality, show key relationships and make testable predictions.

What is a circular economy?

A system where products and materials are kept in use through reuse, repair and recycling instead of take-make-dispose.

Economics

1.2 How do economists approach the world?

Economists separate testable statements from value judgements and use simplified models, tested against evidence, to explain how economies work. Study guide, 3 practice questions with markschemes and 4 flashcards. Free.

Positive vs normative economics · models, assumptions and ceteris paribus · logic, hypotheses and empirical evidence · value judgements and equity · history of economic thought from classical to modern · rise of behavioural and circular-economy thinking

Practise all 3 questions Study 4 flashcards

Study guide

Positive and normative statements

A positive statement describes or predicts and can, in principle, be checked against data: "A rise in bus fares reduced passenger numbers by 6%." It may be false, but it is testable. A normative statement contains a value judgement about what ought to happen: "The city should keep fares low for students." Words like should, fair, too high and better usually signal normative content. Policy debates mix both: evidence tells us what a policy is likely to do, values decide whether those outcomes are desirable.

Models, assumptions and ceteris paribus

The real economy has millions of interacting decisions, so economists build models: simplified representations that isolate a few variables. The demand and supply diagram, the PPC and the circular flow are all models. Models depend on assumptions, for example that consumers aim to maximise satisfaction or that firms aim to maximise profit. The key assumption is ceteris paribus: all other things held constant, so the effect of one variable can be studied alone.

A good model is judged by how useful its predictions are, not by how realistic every assumption is. Still, when assumptions are badly wrong, predictions fail, which is why later topics (behavioural economics in 2.4) challenge some of them.

The scientific method in economics

Economists form a hypothesis ("higher minimum wages reduce youth employment"), use logic to derive predictions, then test them with empirical evidence such as statistics or natural experiments. Unlike chemists, they rarely run controlled experiments on whole economies, so it is hard to separate cause from correlation. Evidence can support a theory but never prove it beyond doubt, and results may differ between countries and time periods.

Value judgements and equity

Equity means fairness, which is different from equality (everyone having the same). Whether a distribution of income is equitable is a normative question. Economists can measure inequality, but deciding how much is acceptable depends on values.

How economic thinking has changed

Classical thought (late 1700s onwards) stressed that markets guided by self-interest and competition could allocate resources well, with limited government.
Marxist critiques argued that markets concentrate wealth and exploit labour.
Neoclassical economics added marginal analysis and rational, maximising agents, the basis of most diagrams in this course.
Keynesian economics, after the Great Depression, argued that markets may not fix mass unemployment alone, so government spending matters.
Monetarist and new classical thinking in the 1970s-80s put more trust in markets and focused on controlling inflation.
Behavioural economics draws on psychology to show that people make systematic errors.
Circular economy thinking replaces the linear "take, make, dispose" model with one where products are designed to be reused, repaired and recycled, keeping materials in use and cutting waste.

Common mistakes

Thinking a positive statement must be true. It only needs to be testable.
Labelling any statement with numbers as positive. "Taxes of 40% are too high" is normative despite the number.
Treating ceteris paribus as realism. It is a deliberate simplification.
Confusing equity with equality.

Exam tips

10-mark questions: explain why models simplify, give a concrete model from the course and show how ceteris paribus lets you isolate a cause.
15-mark questions: evaluate the usefulness of models built on rational-agent assumptions. Credit their clarity and predictive power, then use behavioural evidence and real-world complexity as limits, and reach a judgement.
When asked to distinguish statements from an extract, quote the words that make each one positive or normative.

Cheat sheet

Idea	Key point
Positive	testable, may be true or false
Normative	value judgement; "should", "fair", "too much"
Model	simplification of reality
Ceteris paribus	hold everything else constant
Method	hypothesis → logic → prediction → test with data
Equity vs equality	fair vs identical

Schools of thought in order: classical → Marxist → neoclassical → Keynesian → monetarist / new classical → behavioural → circular economy
Linear economy: take, make, dispose · Circular: reduce, reuse, repair, recycle
Limits of economic evidence: no controlled experiments, correlation is not causation, results vary across places and times

Key definitions

Positive statement: A statement about what is, was or will be that can be tested against evidence.
Normative statement: A statement that expresses a value judgement about what ought to be.
Economic model: A simplified representation of reality that focuses on a few key variables to explain or predict behaviour.
Ceteris paribus: The assumption that all other relevant factors are held constant while one variable changes.
Hypothesis: A testable proposition about the relationship between economic variables.
Equity: Fairness in the distribution of income, wealth or opportunity, which is a normative idea.
Circular economy: A system in which products and materials are kept in use through reuse, repair and recycling, reducing waste and new resource use.
Behavioural economics: A branch of economics that uses insights from psychology to explain why people often depart from fully rational choices.

Practice questions

SLPaper 2Foundation

Question 1

Extract: Hillport transport review

The city's economic advisers reported: Statement 1: "When bus fares were cut by 15% last year, the number of journeys rose by 6%." A councillor replied: Statement 2: "The council ought to make buses free for all students because it is the fair thing to do." The advisers used a simple demand model to predict passenger numbers, assuming other factors such as fuel prices and incomes stay unchanged.

(a) [1]

Identify which of the two statements is normative.

Markscheme

1 Statement 2 ("the council ought to ...") is normative

(b) [3]

Distinguish between positive and normative economic statements.

Markscheme

1 Positive statements are about what is, was or will be
1 and can be tested/refuted with evidence
1 Normative statements contain value judgements about what ought to be and cannot be proved true or false

(c) [4]

Explain why economists use the assumption of ceteris paribus when building models such as the one used by the council's advisers.

Markscheme

1 Ceteris paribus means all other factors are held constant
1 Real markets are affected by many variables at once
2 Holding others constant isolates the effect of one variable (e.g. the fare change) so a clear cause-and-effect prediction can be made

SLPaper 1Challenging

Question 2

(a) [10]

Explain why economists build models based on simplifying assumptions.

Markscheme

1 Defines the key economic terms used in the question accurately
2 Explains that the economy is complex and models simplify reality to focus on key relationships
2 Explains the role of assumptions such as rational behaviour and ceteris paribus
2 Explains how models generate hypotheses that can be tested against empirical evidence
2 Uses an example of a model, e.g. demand and supply or the PPC, with a supporting diagram
1 Explains that models allow predictions useful for policy-makers

(b) [15]

Evaluate the claim that economics can be considered a science.

Markscheme

1 Defines economics as a social science
3 Explains the scientific features: hypotheses, data collection, testing and revising theories
2 Uses a real-world example, e.g. evidence on the effect of a sugar tax on purchases
2 Evaluates: controlled experiments are rarely possible; many variables change at once
2 Evaluates: human behaviour is not always predictable, as shown by behavioural economics
2 Evaluates: value judgements and normative goals influence which questions economists study
2 Evaluates: field experiments and natural experiments partly overcome these limits
1 Reaches a supported conclusion

SLPaper 1Standard

Question 3

(a) [10]

Explain how the idea of a circular economy differs from the traditional linear model of production and consumption.

Markscheme

1 Defines the key economic terms used in the question accurately
2 Describes the linear model: take resources, make products, dispose of waste
2 Describes the circular model: products designed to be reused, repaired, remanufactured and recycled
2 Explains that the circular economy reduces resource depletion and waste, linking to sustainability and scarcity
2 Explains why markets may not move to circular production on their own (external costs of waste not priced)
1 Uses a real-world example, e.g. a phone maker taking back devices to recover materials

Key facts

Positive vs normative statement?: Positive: factual, testable with evidence. Normative: contains a value judgement about what ought to be.
What does ceteris paribus mean?: "All other things being equal": other variables are held constant to isolate the effect of one change.
Why do economists use models?: To simplify a complex reality, show key relationships and make testable predictions.
What is a circular economy?: A system where products and materials are kept in use through reuse, repair and recycling instead of take-make-dispose.