Fragments, Fusions & Splices – Understanding Grammar
Among the many errors in sentence structure common in English prose are sentence fragments, fused sentences and comma splices. All three are caused by a misunderstanding of the ways in which independent and dependent clauses can be successfully used and combined, so a basic comprehension of these different types of clauses is necessary. An independent clause contains a subject and a verb and also expresses a complete thought. ‘She wrote an article every month’ is an independent clause, and, like all independent clauses, it is also a correct sentence. A dependent clause, on the other hand, contains a subject and a verb, but it does not express a complete thought. ‘As she wrote her article every month’ is a dependent clause because it leaves the reader wondering ‘What? What happened as she was writing?” A dependent clause cannot be a complete sentence.

A sentence fragment occurs when a writer uses a dependent clause or other incomplete thought such as a phrase or single word as though it were a complete sentence. For example, ‘Before I completed the second trial’ may be a perfectly acceptable part of a larger complex sentence, but it is a dependent clause and cannot stand on its own. ‘I completed the second trial’ can, but the temporal qualifier ‘before’ is gone. To retain that dependent marker and its meaning, an independent clause must follow or precede the dependent clause. ‘Before I completed the second trial, I recruited participants for the third’ or ‘I recruited participants for the third trial before I completed the second one.’ Notice that a comma is required between the two clauses if the dependent clause precedes the independent clause, but is not always necessary when the independent clause comes first.

A fused sentence, which is also called a run-on sentence, is the result of using two independent clauses back to back without any punctuation between them. ‘I devised new methods for the third trial the sample size was paradoxically reduced’ is an excellent example of a run-on sentence because it also demonstrates how unclear language can become when the rules of grammar and punctuation are neglected. Corrections would vary depending on what is intended by ‘paradoxically’ and particularly on whether there is a direct relationship between the ‘new methods’ and the ‘sample size.’ It would probably be best from a stylistic perspective to eliminate that shift from the active voice (I devised) to the passive voice (was…reduced) as well, though to keep it the sixth example below would work. Possible correct versions include:
• I devised new methods for the third trial, paradoxically, by reducing the sample size,
• I devised new methods for the third trial and adopted a paradoxical strategy by reducing the sample size as well.
• I devised new methods for the third trial; however, my colleague reduced the sample size.
• I devised new methods for the third trial after my colleague decided to reduce the sample size.
• I devised new methods for the third trial, but I also made the paradoxical decision to reduce the sample size.
• I devised new methods for the third trial. The sample size was paradoxically reduced.
As the corrected examples show, the grammatical solution can come in a variety of ways, from separation into two complete sentences via a full stop to a closer connection of the two thoughts in a single successful sentence via punctuation (comma and semicolon), a coordinating conjunction (‘and’ and ‘but’), a dependent or independent marker word (‘after’ and ‘however’) and more subtle shifts related to these changes.

A comma splice is very similar to a run-on sentence, but instead of no punctuation, there is a comma between the two independent clauses: ‘I devised new methods for the third trial, the sample size was paradoxically reduced.’ The same corrections apply here: a full stop can produce two sentences; a semicolon with or without a word such as ‘however’ will join the two clauses successfully into one sentence, as will a comma and a coordinating conjunction; or one clause can be rendered dependent through an appropriate marker word.

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