A full stop indicates a complete end to a sentence; a comma indicates a slight change in direction of the sentence. A comma can also be used to break up a sentence into different sub clauses.
When to Use a Comma
1. Linking main clauses.
Keynes was an economist. Keynes was intelligent. Keynes was born in England
Each of these 3 sentences is grammatically correct, however, it makes for stilted reading. We can combine these 3 clauses into one sentence.
- Keynes was an intelligent economist, who was born in England.
2. After an introductory element of a sentence.
Monetarism is the study of Money supply. We could add an introductory sentence to this.
- Popularised by Milton Friedman, Monetarism is the study of Money Supply.
These introductory phrases are often known as prepositional phrases; it literally means, “to go before”.
- One more example: In many different countries, economists often fail to predict recessions.
3. Adding a subordinate clause at the end of a sentence.
A subordinate clause is a phrase that couldn’t make a sentence on it its own.
- Economists are very bad at predicting the future, although occasionally they get it right.
The first phrase is a sentence on its own, the last phrase adds to the initial statement, and so is a subordinate clause.
4. Parenthetical Elements in a sentence.
These involve words like “however”, “in fact”, “of course”, and “for example”. These words help to link a sentence together; they need a comma before and after.
- Economics is termed the dismal science, however, occasionally it can be fun to study Economics.
A common mistake, however, is to only include one comma after the “however,” and not before.
- The latest inflation news was disappointing, in fact, the Bank of England was very concerned.
This is a term used to rename a noun.
- John Maynard Keynes, Britain’s most famous economist, died in 1946.
- Economics, the study of scarcity, is growing in popularity.
6. Link Between lists.
- The benefits of studying economics include: higher pay, understanding of life, and boundless joy.
7. Comma before quotation
- Milton Friedman repeatedly said, “to control inflation, you must control the money supply”
Sometimes you can use a semi colon, or even colon, before a quote.
8. Surrounding the name or title of a person
- Will you, Tom, do that essay?
- No, Richard, I have better things to do.
9. Use comma to separate statement from question.
- Monetarism is rubbish, do you agree?
10. Use a comma for sentences beginning with yes, well, or now.
- Well, it would be unusual to pass Economics without studying.
11. Use a comma between two adjectives when the word and could be put between them.
- Keynes was an intelligent, innovative economist.
12. Use a comma between independent clauses.
- Keynes was a member of the Bloomsbury set, and he studied hard to become a great economist.
Note: Each phrase could stand alone as a sentence.
Books on Using The Comma