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Apostrophes and hyphens

Apostrophes

Apostrophes are used for two reasons. They can be used to indicate that a letter(s) has been omitted (eg doesn’t = does not) or to show possession (eg the student’s report).

Contractions such as ‘doesn’t’ should be avoided in academic writing. Write the full form ‘does not’.

Possession

The apostrophe is used with a noun to show that something belongs to the noun.

Exception: Do not use an apostrophe to indicate possession with the word ‘it’.
  • it’s = it is
  • its = possession

Example: Lenin’s theory, this student’s conclusion

The noun is singular, the apostrophe goes before the ‘s’.

Example: the witness’s evidence

The above rule still applies in the case of words already ending in ‘s’.

Example: the Achilles’ heel (not the Achilles’s heel), Higgins’ hypothesis (not Higgins’s hypothesis)

In the case of a name ending in ‘s’, it is not necessary to add a further ‘s’.

Example: children’s studies (not childrens’ studies)

Special plurals not ending in ‘s’, eg children, the noun is treated as a singular noun.

Example: the researchers’ teamwork

The noun is plural (so there is more than one researcher), the apostrophe goes after the ‘s’.

Example: The last decade has seen a considerable increase in inflation rates’.

This example is incorrect because an apostrophe has been used where there is no possession. Do not use an apostrophe where there is no possession.

Hyphens

Hyphens are a confusing area and there is some disagreement about whether to hyphenate certain words or not. Generally, always make sure that your use of hyphenated words is systematic and try to be consistent with the conventions used in important journals in your field. Alternatively, check in a good, up-to-date dictionary.

Two areas where hyphens are commonly used are given below:

Use hyphens when attaching a prefix to a commonly used noun.

Example: by-product, mass-produced

If you form a compound adjective before a noun (eg a six-sided figure) you must connect the two (or more) adjectives with a hyphen.

Example:

  • PhD students work a fifty-hour week
  • You must give a fifteen-minute presentation
  • A well-managed project

However, you should not use a hyphen after an adverb which ends in –ly.

Example: an incorrectly labelled graph.