science

Ordinary good

Ordinary good is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Ordinary good rather than just read about it. In short: An ordinary good is a microeconomic concept used in consumer theory. It is defined as a good which creates an increase in quantity demanded when the price for the good drops or conversely a decrease in quantity demanded if the price for the good increases, ceteris paribus.

Key takeaways

Ordinary good belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Ordinary good to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Ordinary good from memory before moving on to harder problems.

Reference excerpt

An ordinary good is a microeconomic concept used in consumer theory. It is defined as a good which creates an increase in quantity demanded when the price for the good drops or conversely a decrease in quantity demanded if the price for the good increases, ceteris paribus. It is the opposite of a Giffen good. Since the existence of Giffen goods outside the realm of economic theory is still contested, the pairing of Giffen goods with ordinary goods has gotten less traction in economics textbooks than the pairing normal good/inferior good used to distinguish responses to income changes. The usage of "ordinary good" is still useful since it allows a simple representation of price and income changes. A normal good is always ordinary, while an ordinary good can be a normal good, an inferior good or "sticky". In economics, "stickiness" describes a situation in which a nominal price is slow to adjust or resistant to change.

Distinction between income and price effects

See also Supply and demand Consumer theory Giffen good Inferior good Normal good Capital good

References

Hal Varian, Intermediate Microeconomics: A Modern Approach, Sixth Edition, chapter 6

Worked examples

Example 1 — a first encounter with Ordinary good

Start with the simplest possible case. Write down what Ordinary good claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Ordinary good before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Ordinary good ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Ordinary good

In research: Ordinary good appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Ordinary good in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Ordinary good is common in secondary-school and first-year university syllabi. It links to neighbouring topics Goods, Microeconomics stubs, so understanding it makes those chapters shorter.
In everyday life: Look for Ordinary good outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Ordinary good in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Ordinary good means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Ordinary good out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Ordinary good in simple terms?

Why does Ordinary good matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Ordinary good?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Ordinary good.