Run ons are probably one of the most common error we see in writing. There are two types of run ons:

A fused sentence occurs when two or more complete sentences (independent clauses) are joined with no punctuation.
A comma splice (a form of a run on) occurs when two or more complete sentences are joined only with a comma, which is not strong enough punctuation.

For this lecture, carefully review the information on run on sentences below. You will be asked to complete a quiz on run on sentences next:

A run-on sentence occurs when two or more independent clauses (also known as complete sentences) are connected improperly.

Example: I love to write papers I would write one every day if I had the time.

There are two complete sentences in the above example:

Sentence 1: I love to write papers.

Sentence 2: I would write one every day if I had the time.

One common type of run-on sentence is a comma splice. A comma splice occurs when two independent clauses are joined with just a comma.

Example of a comma splice: Participants could leave the study at any time, they needed to indicate their preference.

Sentence 1: Participants could leave the study at any time.

Sentence 2: They needed to indicate their preference.

Some comma splices occur when a writer attempts to use a transitional expression in the middle of a sentence.

Example of a comma splice: The results of the study were inconclusive, therefore more research needs to be done on the topic.

Sentence 1: The results of the study were inconclusive

Transitional expression (conjunctive adverb): therefore

Sentence 2: More research needs to be done on the topic

To fix this type of comma splice, use a semicolon before the transitional expression and add a comma after it. See more examples of this on the semicolon page.

Revision: The results of the study were inconclusive; therefore, more research needs to be done on the topic.

Correcting Run-On Sentences

A run-on sentence can be fixed by connecting its parts correctly. There are several ways to connect independent clauses.

Use a period. The easiest way to fix a run-on is to split the sentence into smaller sentences using a period. This revision works especially well with longer sentences. Check, however, to make sure that this solution does not result in short, choppy sentences.
Revision example: I love to write papers. I would write one every day if I had the time.

Use a semicolon. Inserting a semicolon between independent clauses creates a grammatically correct sentence. Using a semicolon is a stylistic choice that establishes a close relationship between the two sentences.
Revision example: I love to write papers; I would write one every day if I had the time.

Use a comma and a coordinating conjunction. A comma, paired with a coordinating conjunction (e.g., "and," "but," or "or"), corrects a run-on sentence. This method emphasizes the relationship between the two clauses.
Revision example: I love to write papers, and I would write one every day if I had the time.

Use a subordinating conjunction. Turn one of the independent clauses into a dependent clause. A subordinating conjunction (e.g., "because," "unless," and "although") connects two clauses to create a complex sentence. This option works to cement the relationship between the two parts of the sentence and may improve the flow of the clauses.
Example: Because I love to write papers, I would write one every day if I had the time.

However you decide to revise for run-on sentences, remember that maintaining sentence variety helps to keep the writing clear and interesting for your readers.