WRITING SKILLS

Punctuation is a system of signals you give to your reader to show how the grammar of the sentences is supposed to work.

(Northedge 1990)

Punctuation has two main tasks: a functional one of making meaning clear, and a cosmetic one of enhancing style. There is much disagreement among 'authorities' over punctuation. Attempting to conform to so-called 'rules' of grammar sometimes leads away from the clarity that you should aim for. It would be wise to give priority to making your meaning clear when deciding how your writing should be punctuated.

A passage from a translation of a work written in 1466 by Aldus Manutius is quoted by Gowers (1986: 152). It could have been written with the PhD thesis in mind: 'I myself have learned by experience, that, if ideas that are difficult to understand are properly separated, they become clearer, ...' You may feel that, if so many commas are necessary, a simpler sentence construction is preferable, e.g. 'In my experience, ideas that are difficult to understand become clearer if they are properly separated.'

In the following pages we offer some simple guidelines on the use of the most commonly encountered punctuation.

Let your reader know when to pause by using various punctuation marks:

New paragraph (NP) longest break

Full stop (.)

Semicolon (;)

Comma (,) shortest break

Dashes and colons also indicate a break, but are used in slightly different circumstances.

A new paragraph usually marks the start of a new subject. A common fault is to use new paragraphs too frequently. Use short paragraphs to emphasise a point and longer ones to avoid your work becoming too disjointed. Beware not to have any very long paragraphs since they can look daunting to read.

A full stop marks the end of a sentence. How long should sentences be? Conveying one point per sentence is a good guide, but occasionally throw in a longer sentence to vary the tone. Use the length of your sentences to help emphasise important points.

A semicolon can be used in a number of ways: it indicates a pause; it can separate items of a list; it joins closely related clauses.

The comma indicates the shortest pause. Commas can change the meaning of your sentence.

The colon (:) is used after a general statement that precedes a related statement that is more specific,

e.g. The soil used contained: one part sand; two parts peat; and one part jelly beans.

Hyphens can be used to join words (hyphenate), e.g. well-known, co-author and X-ray are all legitimate examples of hyphenation. Booth (1995) advises authors not to use hyphens when inventing new terms, for example Q effect or perhaps "eat and run strategy". NB "T test" is NOT HYPHENATED.

Dashes can also be used to separate words. Dashes can be inserted - as I have done here - to indicate a pause longer than a comma. It is best to use dashes sparingly.

Similar insertion of a small phrase into a sentence can be achieved using parentheses (round brackets). A sentence should (given thought) be able to stand alone if the bracketed phrase is ignored. If the remark is a sentence in itself, then it is usually best to place this at the end of the parent sentence. (Give it its own capital letter and full stop.)

Reading your work out loud can help indicate where your writing needs re-phrasing.

One of the most common faults in writing is the overuse of some punctuation marks. Quotation marks, or inverted commas, are frequently overused. One use that should be carefully restricted is the placing of words or phrases within quotation marks to indicate that they are being used in some special way, such as technically or colloquially.

Quotation marks are heavily used in academic work for a very good reason: we often quote from the work of others. If quoting material in a language other than English, follow published practice where available, or seek advice e.g. from your supervisor.

There are two recognised differences of practice in the use of quotation marks, British style and American style. The distinctions between the two styles are significant and care must be taken to use one or other system correctly and consistently.

British

British English uses single quotation marks for dialogue or quoted material in text. Double quotation marks are reserved for quotes within quotes. In British style other punctuation, such as full stops, falls outside the quotation marks, unless the punctuation is part of the quoted material or the material is itself a complete sentence.

American

American English uses double quotation marks for quoted material in a text and for dialogue. Single quotation marks are used for quotes within quotes. Other punctuation, such as full stops (called periods in American English), falls inside the quotation marks, regardless of whether it forms part of the punctuation of the quoted material.

If the quotation is longer than 40 words, do not use quotation marks. Separate the quotation from the body of your text by a line space above and below it and indent the quoted material from the left.

• apostrophes are used in making the possessive form of singular words by adding 's
• in plural words and in some singular words ending (e)s, the possessive may add an apostrophe alone, for example: secretaries' office; James' laboratory.
• it is often more clear if you avoid a possessive with apostrophe and use the longer form 'of (the)' in order to avoid confusion.
• apostrophes are used to show missing letters or figures (for example: can't, I'll, they're, in '86, in the '90s), though such abbreviations are best avoided in scientific writing.
• it's means 'it is'; its means 'of it'
• apostrophes are not used to form plurals in the case of initials, figures or abbreviations: PCBs,1990s, SGs
• initials form possessives in the normal way: a PCB's molecular weight, PCBs' toxicities

Use the 'spell check' facility on any word processing package as a fast way to correct spelling mistakes. Always back this up with proof reading as a spell check cannot detect cases where you have used the wrong word.

There are acknowledged and acceptable spelling differences among the varieties of English: American English, British English etc. Take advice from your supervisor or a journal's Instructions for Authors in deciding which variety of English to use. Be consistent in your use of that variety of English and in keeping to its internal rules.

It is beyond the scope of a document of this nature to attempt to teach English grammar in any depth. In practice, we probably all behave as George Orwell recommended when he said that grammar was 'of no importance so long as we make our meaning plain' (quoted in Inman 1994: 65). There are, however, prescriptive rules based upon what is taken to be grammatically correct in standard English. Failure to keep to these rules may annoy and distract some readers, making them less likely to be influenced in the way the writer intended.

What we will look at below are a few rules and examples that may help us to avoid obvious yet common mistakes of standard English grammar. These examples are neither exhaustive nor in any order of priority but are included as staff at the University of Leicester have identified them often in students' work.

Grammar: some guidelines

Write in complete sentences unless you have a very good reason not to do so, e.g. for emphasis

Remember that sentences always have a main verb and a subject

Make sure that the main verb in a sentence 'agrees with' its subject, e.g. that a singular verb has a singular subject.

Avoid using double negatives because they can be difficult to work out.

Generally avoid so-called split infinitives, e.g. 'to boldly go ...' because they annoy pedantic readers. Only split an infinitive if the alternative produces ambiguity, e.g.

'Some of the hailstones were of such size that they failed completely to melt before they reached the ground.'

Did they hit the ground partly melted or completely frozen?

Avoid participles (-ing words) without clear reference to the person/thing performing the action, else your writing may be ambiguous.

'Coming downstairs, a light bulb dropped at my feet and smashed.'

'When attempting to revitalise the inner cities, the indigenous population often gets the worse deal.'

Avoid using pronouns such as 'this', 'these' to refer to something or someone mentioned previously, because your writing may be ambiguous. For example, to whom does 'she' refer below?

'After the surgeon had finished operating on the patient, she was able to go home to have dinner with her family.'

Either, neither, each, every take singular verbs

Minority and majority take plural verbs

None may take singular or plural

You will not often use personal pronouns in scientific writing but, if you do, take care to use personal pronouns correctly: I and me, he and him etc. Problems arise in case such as:

'He gave it to John and I' This is wrong

If in doubt over sentences containing 'and' followed by a personal pronoun, think of sentences in which personal pronouns stand alone:

'He gave it to I' This is clearly wrong. Try 'me'

'He gave it to (John and) me' This is correct

As the subject of a verb, 'John and I' would be correct, e.g.

'John and I gave it to him'

back to contents

© University of Leicester, 1997. Writing Skills for Postgraduates and Other Research Scientists, Lucy Birkinshaw and Professor Robert Smith. Based on a pamphlet originally prepared by Robert Ash for the Faculty of Social Sciences. Web-editors: Ted Gaten and Magnus Johnson

Last updated: May 2003
Biology Web Maintainer
This document has been approved by the head of department or section.