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SENTENCE PUNCTUATION ERRORS
by Kathy McLain, M.A.   Correctly Linking Sentences | Comma Splices | Run-ons | Sentence Fragments
How Should Complete Sentences Be Linked Together?
There are three types of sentence punctuation errors that you may find noted by your instructor in your writing--a comma-splice, a run-on, or a sentence fragment.  All of these errors involve incorrectly punctuating a complete sentence.  These errors are serious errors because you signal to the reader that you as a writer do not know how to punctuate a complete sentence correctly.  Before you can understand or revise these errors, you must understand how complete sentences are linked together.

There are only two ways of linking two complete sentences together, (1) using a comma + a coordinating conjunction or (2) using a mark of punctuation.

1.  Using a comma + a coordinating conjunction

complete sentence 1	comma + for	complete sentence two
complete sentence 1	comma + and	complete sentence two
complete sentence 1	comma + nor	complete sentence two
complete sentence 1	comma + but	complete sentence two
complete sentence 1	comma + or	complete sentence two
complete sentence 1	comma + yet	complete sentence two
complete sentence 1	comma + so	complete sentence two

Example:  The boy went to the store, but he never returned.
                       sentence 1       comma + but     sentence 2

There are only seven coordinating conjunctions.  You should memorize them.  If you do not memorize them, you cannot punctuate sentences correctly  This rule does not say that every time you use these conjunctions you use a comma, only when there is a complete sentence on either side of the comma + the coordinating conjunction.  Be sure to check the other uses for the comma since these rules will further clarify other times when you use commas with coordinating conjunctions.

2.  Using a mark of punctuation--a period, a semi-colon, a colon, a question mark, or a exclamation point.

complete sentence 1	. (period)	complete sentence two
complete sentence 1	; (semi-colon)	complete sentence two
complete sentence 1	: (colon)	complete sentence two
complete sentence 1	? (question mark)	complete sentence two
complete sentence 1	! (exclamation point)	complete sentence two

In the preceding sentences the period, the semi-colon, and the colon say something slightly different to the reader.  The period says to the reader, "Stop. These are two separate sentences."   The period is the most frequently used.  The semi-colon's prime grammatical function is to separate two complete sentences that are closely related in meaning.  Hence, the semi-colon says to the reader, "These are two complete sentences that are closely related in meaning."  The semi-colon is used occasionally.  The colon tells the reader to look at the complete sentence that follows.  When a colon separates two complete sentences, it says to the reader, "These are two complete sentences, but pay attention to the second sentence." The colon is rarely used to separate two complete sentences.

Example:

The boy went to the store.  He never returned
(Period says stop.  These are two complete sentences.)

The boy went to the store; he never returned
(Semi-colon says these are two complete sentences closely related in meaning)

The boy went to the store:  He never returned
(Colon says these are two complete sentences.  Pay attention to the second sentence.)

What Is a Comma Splice?
A comma splice is a serious punctuation error in which you separate two complete sentences with a comma.  To solve this error you must examine the two rules above to decide which method is most logical to punctuate the sentence correctly.

Comma splice:  The boy went to the store, he never returned

The easiest solution to this error is to use rule number two for linking complete sentences.  Delete the comma and add according to the situation the correct end mark of punctuation.

Correction Using Rule 2:  The boy went to the store.  He never returned

If the context of the sentence allows, you might also correct the above comma-splice by using rule number one.

Correction Using Rule 1:  The boy went to the store, and he never returned.

A comma-splice can be easily corrected.  You can avoid them in future writing if you will memorize the two methods for linking complete sentences together.
 

What Is a Run-on Sentence?
A run-on sentence, also called a fused sentence, is two complete sentences linked together without any mark of punctuation.  This error usually occurs in two distinct forms: two sentences linked together without any mark of punctuation and two sentences link together with a coordinating conjunction but missing the necessary comma to link the two sentences together correctly. The second sentence might also be an incomplete sentence.

Run-on Sentences:

The boy went to the store he never returned
The boy went to the store and he never returned

One solution to the first run-on sentence is to add an end mark of punctuation.

Correction Using Rule 2:

The boy went to the store.  He never returned.

One solution to the second run-on sentence is to add a comma to correctly punctuate these two complete sentences.

Correction Using Rule 1:

The boy went to the store, and he never returned.

What Is a Sentence Fragment?
A sentence fragment is another type of serious error.  A sentence fragment is a group of words you have punctuated as a complete sentence, but this group of words is not a complete sentence.  Complete sentences must have a subject ("man" / "he")  and a verb ("is" / "running").  The sentence could be as simple as "It rained."  These two words constitute a compete sentence because one is a subject, "it," and the other is verb, "rained."  At times, sentence fragments are created by punctuation errors.  At other times, sentence fragments are created by writing errors.  Sentence fragments, unless used for a specific stylistic reason in your writing that you must be able to justify, are unacceptable in college level writing.

Sentence Fragment:

After the boy went to the store.  He never returned.
                sentence fragment

The sentence fragment in this first example occurred because the writer failed to recognize that this introductory element cannot be punctuated as a complete sentence because the word "after" makes this sentence (clause) a subordinate sentence (subordinate clause) that must be linked to the main sentence (main clause) with a comma.  This is an example of a sentence fragment created by a punctuation error.  No rewriting needs to take place because the error occurred as a result of incorrectly linking sentences parts together with punctuation.

Correction:    After the boy went to the store, he never returned.

Another type of sentence fragment occurs when the writer punctuates a group of words as a sentence when grammatically it is not.  This error occurs because the sentence lacks a subject or a verb.

Sentence Fragment:

Going to the store and never returning
(This group of words has only verbs but no subjects.)

Correction:

The boy went to the store and never returned.
(This is now a complete sentence because there is a subject, "the boy" and the verbs "went" and "returned.")

This group of words punctuated as a sentence cannot be revised correctly by a punctuation mark.  Instead the group of words needs to be revised to include a subject.  Of the two types of sentence fragments, usually the type missing the subject or verb is more serious because it suggests that the writer does not have the skill to write a sentence.  The sentence fragment created by incorrect punctuation suggests that the writer doesn't know how to punctuate a complete sentence correctly.  Neither error should occur in college level writing.