Twelve Common Errors

Download this Handout PDF

This list includes only brief examples and explanations intended for you to use as reminders while you are editing your papers. If you would like to learn more, consider the following options:

  • Take one of the free grammar, style, and punctuation classes offered by the Writing Center.
  • Set up an appointment for an individual conference in the Writing Center.
  • Confer with your course instructor.
  • Consult a handbook for additional examples and complete explanations

1. Sentence fragments

Make sure each word group you have punctuated as a sentence contains a grammatically complete and independent thought that can stand alone as an acceptable sentence.

Incorrect

Tests of the Shroud of Turin have produced some curious findings. For example, the pollen of forty-eight plants native to Europe and the Middle East.

[2nd sentence = fragment]

Correct

Tests of the Shroud of Turin have produced some curious findings. For example, the cloth contains the pollen of forty-eight plants native to Europe and the Middle East.

Incorrect

Scientists report no human deaths due to excessive caffeine consumption. Although caffeine does cause convulsions and death in certain animals.

[2nd sentence = fragment]

Correct

Scientists report no human deaths due to excessive caffeine consumption, although caffeine does cause convulsions and death in certain animals.

2. Sentence sprawl

Too many equally weighted phrases and clauses produce tiresome sentences.

Incorrect

The hearing was planned for Monday, December 2, but not all of the witnesses could be available, so it was rescheduled for the following Friday, and then all the witnesses could attend.

[There are no grammatical errors here, but the sprawling sentence does not communicate clearly and concisely.]

Correct

The hearing, which had been planned for Monday, December 2, was rescheduled for the following Friday so that all witnesses would be able to attend.

3. Misplaced and dangling modifiers

Place modifiers near the words they describe; be sure the modified words actually appear in the sentence.

Not sure what a modifier is? Check our our FAQ.

Too many equally weighted phrases and clauses produce tiresome sentences.

Incorrect

When writing a proposal, an original task is set for research.

Correct

When writing a proposal, a scholar sets an original task for research.

Incorrect

Many tourists visit Arlington National Cemetery, where veterans and military personnel are buried every day from 9:00 a.m. until 5:00 p.m.

Correct

Every day from 9:00 a.m. until 5:00 p.m., many tourists visit Arlington National Cemetery, where veterans and military personnel are buried.

Still unsure? For more explanation and examples, see our grammar and style FAQ.

4. Faulty parallelism

Be sure you use grammatically equal sentence elements to express two or more matching ideas or items in a series.

Incorrect

The candidate’s goals include winning the election, a national health program, and the educational system.

Correct

The candidate’s goals include winning the election, enacting a national health program, and improving the educational system.

Incorrect

Some critics are not so much opposed to capital punishment as postponing it for so long.

Correct

Some critics are not so much opposed to capital punishment as they are to postponing it for so long.

5. Unclear pronoun reference

All pronouns must clearly refer to definite referents [nouns].

Use it, they, this, that, these, those, and which carefully to prevent confusion.

Unclear:

Einstein was a brilliant mathematician. This is how he was able to explain the universe.

Clear:

Einstein, who was a brilliant mathematician, used his ability with numbers to explain the universe.

Unclear:

Because Senator Martin is less interested in the environment than in economic development, he sometimes neglects it.

Clear:

Because of his interest in economic development, Senator Martin sometimes neglects the environment.

6. Incorrect pronoun case

Determine whether the pronoun is being used as a subject, or an object, or a possessive in the sentence, and select the pronoun form to match.

Incorrect:

Castro’s communist principles inevitably led to an ideological conflict between he and President Kennedy.

Correct:

Castro’s communist principles inevitably led to an ideological conflict between him and President Kennedy.

Incorrect:

Because strict constructionists recommend fidelity to the Constitution as written, no one objects more than them to judicial reinterpretation.

Correct:

Because strict constructionists recommend fidelity to the Constitution as written, no one objects more than they [do] to judicial reinterpretation.

7. Omitted commas

Use commas to signal nonrestrictive or nonessential material, to prevent confusion, and to indicate relationships among ideas and sentence parts.

Incorrect:

When it comes to eating people differ in their tastes.

Correct:

When it comes to eating, people differ in their tastes.

Incorrect:

The Huns who were Mongolian invaded Gaul in 451.

Correct:

The Huns, who were Mongolian, invaded Gaul in 451.

[“Who were Mongolian” adds information but does not change the core meaning of the sentence because Huns were a Mongolian people; this material is therefore nonrestrictive or nonessential.]

For more information on commas see Commas: Punctuating Restrictive and Non-restrictive Modifiers and Punctuating Coordinating Conjunctions and Sentence Adverbs, or take one of the free grammar, style, and punctuation workshops offered by the Writing Center.

8. Superfluous commas

Unnecessary commas make sentences difficult to read.

Unclear:

Field trips are required, in several courses, such as, botany and geology.

Clear:

Field trips are required in several courses, such as botany and geology.

Unclear:

The term, “scientific illiteracy,” has become almost a cliche, in educational circles.

Clear:

The term “scientific illiteracy” has become almost a cliche in educational circles.

For more information on commas see Commas: Punctuating Restrictive and Non-restrictive Modifiers and Punctuating Coordinating Conjunctions and Sentence Adverbs, or take one of the free grammar, style, and punctuation workshops offered by the Writing Center.

9. Comma splices

Do not link two independent clauses with a comma (unless you also use a coordinating conjunction: and, or, but, for, nor, so, yet).

Instead use a period or semicolon, or rewrite the sentence.

Comma splice:

In 1952 Japan’s gross national product was one third that of France, by the late 1970s it was larger than the GNPs of France and Britain combined.

Correct:

In 1952 Japan’s gross national product was one third that of France. By the late 1970s it was larger than the GNPs of France and Britain combined.

Comma splice:

Diseased coronary arteries are often surgically bypassed, however half of all bypass grafts fail within ten years.

Correct:

Diseased coronary arteries are often surgically bypassed; however, half of all bypass grafts fail within ten years.

For more information on commas see Commas: Punctuating Restrictive and Non-restrictive Modifiers and Punctuating Coordinating Conjunctions and Sentence Adverbs, or take one of the free grammar, style, and punctuation workshops offered by the Writing Center.

10. Apostrophe Errors

Apostrophes indicate possession for nouns (“Jim’s hat,” “several years’ work”) but not for personal pronouns (its, your, their, and whose).

Apostrophes also indicate omissions in contractions (“it’s” = “it is”).

In general, they are not used to indicate plurals.

Incorrect:

In the current conflict its uncertain who’s borders their contesting.

Correct:

In the current conflict it is [it’s] uncertain whose borders they are [they’re] contesting.

Incorrect:

The Aztecs ritual’s of renewal increased in frequency over the course of time.

Correct:

The Aztecs’ rituals of renewal increased in frequency over the course of time.

11. Words easily confused

“Effect” is most often a noun (the effect), and “affect” is almost always a verb.

Other pairs commonly confused: “lead”/”led” and “accept”/”except.”

Check a glossary of usage to find the right choice.

Incorrect:

The recession had a negative affect on sales.

Correct:

The recession had a negative effect on sales.
(or) The recession affected sales negatively.

Incorrect:

The laboratory instructor chose not to offer detailed advise.

Correct:

The laboratory instructor chose not to offer detailed advice.

12. Misspellings

Spelling errors are usually perceived as a reflection of the writer’s careless attitude toward the whole project.

Don’t allow your hard work to be marred in this way!

In addition to comprehensive dictionaries, you may want to use electronic spell checks, spelling dictionaries, and lists of frequently misspelled words found in handbooks.