Common Comma Mistakes, Part 1 of 2

For such a small punctuation mark, the comma plays an extremely important role in conveying your meaning to your audience. In speech, you can emphasise your meaning easily using your voice. In writing, punctuation does this job for you. Perhaps you have had the experience of a poorly punctuated email, text message or Facebook post being misinterpreted. You certainly don’t want that to happen when you are writing for university!

Over the course of two articles, we will identify some of the most common comma mistakes and explain how to know when to use the comma. If you can understand and avoid these common mistakes, your written communication will benefit from increased clarity and accuracy of meaning. In this first article, let’s start by looking at using commas around names and with ‘extra information’ clauses. The second article in this set will focus on keeping your noun and verb together and ensuring clarity of meaning when listing.

Using commas around names

One of the most common mistakes in using commas involves giving names in sentences. Ask yourself the question: is the name ‘extra information’ that could be deleted from the sentence with minimal impact on the meaning or is the name essential information in the sentence? In the following examples, the name is provided as extra information. When extra information, not essential to the meaning, is added to a sentence, use commas to show this.

Incorrect: We contacted the Principal of the school Ms Smith for further comment.

Correct: We contacted the Principal of the school, Ms Smith, for further comment.

In this second example, the name and ‘principal’ are essential to one another. In fact, the name is more essential to the sentence than is ‘principal’.

Incorrect: Principal, Ms Smith, provided further information on her school.

Correct: Principal Ms Smith provided further information on her school.

Commas with other ‘extra information’ clauses

As in the first example above, whenever you insert extra information clauses into a sentence, you show the beginning and end of the clause with a comma. You know a clause is just extra information because you could remove it from the sentence without affecting the meaning. In the following example, the incorrectly punctuated sentence is ambiguous. Is the sentence saying that many experiments were conducted but not all of them were in a lab? In this case, no. The intended meaning is that this one experiment ran for 56 minutes and, as extra information, it was conducted in a lab.

Incorrect: The experiment which we conducted in the lab ran for 56 minutes.

Correct: The experiment, which we conducted in the lab, ran for 56 minutes.

The above explanations begin to explain the importance of commas for separating clauses to clearly show the relationships between the information in your sentence. This goes a long way to helping you learn to control comma usage. Using only the above rules for comma usage, your writing will already show improved clarity of expression. However, this is only the first part of this two-part article on common comma errors. For further helpful explanations on some other common comma errors, see Part 2.