GRAMMAR OFFENDER: The Run-on & Comma Splice

Now that you know the difference between a fragment and a sentence you are ready to tackle another common writing error: the run-on and comma splice. Remember, unlike the fragment, a sentence has a subject (the doer or actor) and a predicate (the action) allowing it to stand on its own as a complete thought. Fragments seem to end abruptly, and leave you wanting to ask something like “…and then what?”

What is a run-on sentence?

While a run-on sentence, also known as a fused sentence, might just seem to be the type of sentence that goes on and on without a clear point, the technical grammatical definition of a run-on sentence is one that fuses, or “runs together,” two or more independent clauses (clauses that express a complete thought and could stand on their own as full sentences) without punctuation to separate them.

Run-ons may have nothing between them, or they may have a coordinating conjunction (and, or, nor, but, for, so, yet) but not the comma that needs to accompany the coordinating conjunction when separating two independent clauses.

What is a comma splice?

A comma splice is similar to a run-on in that it joins two independent clauses, but it differs in that the clauses arejoined by a comma. Interestingly, a comma splice is a sentence error—not a comma error, which has to do with punctuation.

Examples of run-on sentences

Every day, millions of children go to daycare with millions of other kids there is no guarantee that none of them are harboring infectious conditions.

Many daycares have strict rules about sick children needing to stay away until they are no longer infectious but enforcing those rules can be very difficult.

Daycare providers often undergo extreme pressure to accept a sick child “just this once” the parent has no other care options and cannot miss work.

Examples of comma spliced sentences

Every day, millions of children go to daycare with millions of other kids, there is no guarantee that none of them are harboring infectious conditions.

Many daycares have strict rules about sick children needing to stay away until they are no longer infectious, enforcing those rules can be very difficult.

Daycare providers often undergo extreme pressure to accept a sick child “just this once,” the parent has no other care options and cannot miss work.

Fixing run-ons and comma splices

Once you find a run-on or comma splice and notice where the two independent clauses “collide” or are “spliced,” you can then decide how best to separate the clauses:

You can make two complete sentences by inserting a period. This is the strongest level of separation.

You can use a semicolon between the two clauses if they are of equal importance; this allows your reader to consider the points together.

You can use a semicolon with a transition word to indicate a specific relation between the two clauses; however, use this sparingly.

You can use a coordinating conjunction following the comma, and this also will indicate a relationship.

Or, you can add a word to one clause to make it dependent.

Examples of fixed run-on and comma spliced sentences

Notice how the sentences from above have been punctuated in the following examples.

Every day, millions of children go to daycare with millions of other kids. There is no guarantee that none of them are harboring infectious conditions.

Many daycares have strict rules about sick children needing to stay away until they are no longer infectious; however, enforcing those rules can be very difficult.

Many daycares have strict rules about sick children needing to stay away until they are no longer infectious, butenforcing those rules can be very difficult.

Daycare providers often undergo extreme pressure to accept a sick child “just this once” because the parent has no other care options and cannot miss work.

Writer’s Tip
If you struggle with run-ons read your paper out loud.  The run-on sentences will trip you up: you’ll want to pause or otherwise come to some sort of end when you hit the end of an independent clause, but a run-on, with its lack of punctuation, doesn’t signal you to do that.

If you struggle with comma splices, find all the commas in your paper, look at the text before and after the comma, and decide whether they can stand alone—do they both contain a subject and a verb to make a complete thought? If so, then you have found the comma splice!