Quick Tips: Common Comma Errors
Commas are the bane of a copy editor’s existence. The rules of proper comma usage are vast and nearly impossible to list in something titled a Quick Tip. However, for today’s quick tip, here are some of the common comma errors we see on a regular basis:
A misplaced comma before a conjunction and a dependent clause:
Tom made his bed, and went to work.
Since there is only one subject in the sentence, the second phrase is dependent on the first. There should not be a comma.
Tom made his bed and went to work.
Conversely, a missing comma before a conjunction between two independent clauses:
I lost my shoe but my mom found it under my bed.
This sentence is made up of two independent clauses. I lost my shoe and my mom found it under my bed. That being the case, there should be a comma before the coordinating conjunction.
I lost my shoe, but my mom found it under my bed.
I need a new purse, this one is old and ratty.
Comma splices take two perfectly good phrases and connect them together with a comma without the use of coordinating conjunctions. To correct this, you can add a coordinating conjunction, break the sentence into two sentences, replace the comma with a semicolon, or reword.
I need a new purse, for this one is old and ratty.
I need a new purse. This one is old and ratty.
I need a new purse; this one is old and ratty.
I need a new purse because this one is old and ratty.
Restrictive and nonrestrictive appositives:
Fred’s wife Ginger is a great dancer.
This is an example of a nonrestrictive appositive. Fred probably only has one wife—Ginger. So her name can be removed from the sentence without skewing its meaning. Therefore her name should be set off by commas.
Fred’s wife, Ginger, is a great dancer.
However, a restrictive appositive provides essential information about the noun and should not be set off by commas.
Helen’s daughter Julie is arriving home from college tonight.
Helen could have multiple daughters, so Julie’s name is essential to the sentence.
Commas with direct address:
Good afternoon Miss Murphy.
Commas are used to set off names in direct address.
Good afternoon, Miss Murphy.
For more tips, see my article on appositives here.