Week 2 - Run-on Sentences and Punctuation

This week we're talking about run-on sentences, broadly defined as sentences containing two or more independent clauses with inadequate punctuation separating them. The kinds of run-on sentences we encounter most often these days are called "comma splices" -- an example is shown here:

This week we're talking about run-on sentences, the ones I see most often are called "comma splices."

The two clauses in the previous example are independent clauses, clauses that can stand on their own, and they need to be separated by a stronger punctuation mark than a comma. The safest choice is to use a period, since we have two complete sentences and neither is dependent on the other. The result would be:

This week we're talking about run-on sentences. The ones I see most often are called "comma splices."

I've seen lots of examples of comma splices in memos and business letters recently, especially at the end when the writer is wrapping up:

Amy, I'm really glad we had a chance to talk this week, please call me if you need more information.

As in the previous example, the two clauses in this run-on sentence are independent and should be separated by a period. One way to test for this situation is to read the sentence back to yourself and see whether you pause at the comma as much as you would at the period separating two other sentences. If you do pause more than you would at an ordinary comma, you should be using a period.

Sometimes you can separate independent clauses with a dash or a semicolon instead of a period. The semicolon tends to be more formal than the dash, so the choice may hinge on the kind of writing you're doing. Both of the following examples are fine (but a comma wouldn't be strong enough):

Yesterday was one of the best days of the summer -- we headed straight to the beach.

We prepared well for the annual audit; there were no findings in the final report.

People are often confused about when to use colons and semicolons. Colons are used to announce an example of something, as in this sentence, or a list of items to follow:

There are four important criteria that need to be fulfilled: allowability, allocability, consistency, and reasonableness.

Semicolons are used in lists too, to separate the elements of a list when one or more of those elements contains one or more commas:

Some types of sponsored awards aren't for research: acquiring equipment; collecting, indexing, and archiving museum specimens; conducting surveys; etc.

Using the same level of punctuation between each pair of list elements makes it clear what those elements are:

• acquiring equipment
• collecting, indexing, and archiving museum specimens
• conducting surveys

This last example brings up one other point we need to emphasize. It's very important to include punctuation between each of the adjacent elements of a list. Some writers leave out the last comma, and readers can get confused. The classic example is:

This book is dedicated to my parents, Ayn Rand and God.

Obviously, one more comma clarifies things enormously!