Common Grammar and Punctuation Errors in Dissertations, Essays and Assignments and How to Fix Them
Academic writing must be clear, accurate and professional. Yet even strong researchers fall prey to small grammar and punctuation errors that undermine credibility and readability. Below is a practical guide to the most common mistakes, clear rules and quick editing strategies tailored for dissertations, essays and assignments.
Why this matters
- Small errors distract examiners and readers from your argument.
- Consistent, correct punctuation improves readability and signals attention to detail.
- Fixing these issues is essential before submission or publication.
Most common errors and how to fix them
1. Subject–verb agreement
- Problem: Singular subjects paired with plural verbs (or vice versa).
- Wrong: The list of findings are important.
- Correct: The list of findings is important.
- Fix: Identify the subject (not the intervening phrase). For compound subjects joined by "and," use a plural verb; for "either/or" use the verb that matches the closest subject.
2. Comma splices and run-on sentences
- Problem: Two independent clauses joined only by a comma.
- Wrong: The participant completed the survey, she did not finish the interview.
- Better: The participant completed the survey; she did not finish the interview.
- Alternate: The participant completed the survey, but she did not finish the interview.
- Fix: Use a period, semicolon, or coordinating conjunction (+ comma).
3. Misplaced and dangling modifiers
- Problem: Modifiers that don't clearly attach to the word they describe.
- Wrong: After reading the manuscript, the results were surprising.
- Correct: After reading the manuscript, the researcher found the results surprising.
- Fix: Make sure the subject performing the action is explicit and close to the modifier.
4. Incorrect use of apostrophes
- Problem: Confusing plural with possessive.
- Wrong: The students paper is on page 34.
- Correct: The student's paper is on page 34. (singular possessive)
- Correct plural: The students' papers were returned.
- Fix: Use apostrophes only for possession and contractions (avoid contractions in formal academic writing).
5. Confusion between “which” and “that”
- Rule: Use that for restrictive clauses (no comma); which for non‑restrictive clauses (with comma).
- Restrictive: The method that produced the best results was chosen.
- Non-restrictive: The method, which was expensive, produced the best results.
- Fix: Ask if the clause is essential to the noun’s identity. If not, use commas + which.
6. Incorrect punctuation with quotations
- Rule (academic style): Punctuation placement depends on whether the quote is integrated grammatically.
- Correct: Smith (2019) argued that “data quality is crucial.”
- If quote ends sentence, include period inside quotation marks for American style; follow your chosen style guide.
- Fix: Check your style guide (APA, Chicago, MLA) for quote punctuation rules.
7. Overuse or misuse of the passive voice
- Issue: Excessive passive voice can obscure the actor and weaken clarity.
- Passive: Data were collected and analysed.
- Active (clearer): We collected and analysed the data.
- Fix: Use active voice when clarity and responsibility are important; keep passive for objective tone where appropriate.
8. Faulty parallelism
- Problem: Items in a list not in the same grammatical form.
- Wrong: The study aims to investigate, analysing data, and results are reported.
- Correct: The study aims to investigate, analyse data, and report results.
- Fix: Make verb forms or list elements parallel.
9. Incorrect use of semicolons and colons
- Semicolon: joins related independent clauses or separates complex list items.
- Example: The sample was small; therefore, findings are tentative.
- Colon: introduces a list, quotation or explanation.
- Example: Three factors were identified: cost, time and reliability.
- Fix: Use semicolons for closely related clauses; use colons only after complete sentences.
10. Spelling and homophone errors
- Common pitfalls: affect/effect, its/it's, there/their/they're, principal/principle.
- Fix: Use spellcheck, but also manually verify homophones and discipline-specific terminology.
Quick-reference error table
| Error type | Wrong example | Correct example | Quick fix |
|---|---|---|---|
| Comma splice | The study failed, the sample was biased. | The study failed; the sample was biased. | Use semicolon or add conjunction |
| Subject–verb | The list of results are helpful. | The list of results is helpful. | Identify the true subject |
| Apostrophe misuse | The students results were impressive. | The students' results were impressive. | Use apostrophe for possession only |
| Dangling modifier | While reading the article, conclusions emerged. | While reading the article, the researcher drew conclusions. | Attach modifier to correct subject |
| Which/that | The model, that accounts for bias, is robust. | The model that accounts for bias is robust. | Use that for essential clauses |
A practical proofreading workflow
Follow a staged approach to catch both big-picture and microcopy issues:
- Macro pass: check structure, argument flow and paragraph topic sentences.
- Style pass: consistency of tone, concision and word choice.
- Technical pass: grammar, punctuation, citations, formatting.
- Read aloud and backwards: read sentences aloud and check paragraphs in reverse order to spot errors.
For a detailed, professional approach to proofreading, see How to Proofread Your Dissertation, Essay or Assignment Like a Professional Editor.
Tools and collaborative workflows
- Use readability and grammar tools, but do not rely on them exclusively. Learn to interpret suggestions.
- For collaborative editing use track changes and comments to manage revisions.
Fast self-editing tips under time pressure
- Prioritise common issues: subject–verb agreement, comma splices, apostrophes, and citations.
- Use targeted searches: run a find for "which," "that," "it's," "however," and common homophones.
- See: Self-Editing Strategies Under Time Pressure for Dissertations, Essays and Assignments.
When to hire a professional editor
If your deadline is tight, or you need a final quality check to meet institutional standards, consider a professional editor. A good editor will:
- Improve clarity, consistency and academic tone.
- Ensure style guide compliance and formatting consistency.
- Provide tracked changes and a summary of revisions.
Learn what to expect in: Hiring and Briefing an Academic Editor for Dissertations, Essays and Assignments: What to Expect.
Final proofreading checklist (quick)
- Check subject–verb agreement and verb tenses.
- Fix comma splices and run-ons.
- Correct apostrophes and possessives.
- Make modifiers clear and avoid dangling modifiers.
- Ensure parallel structure.
- Verify punctuation with quotations and citations.
- Run spellcheck and manually check homophones.
- Confirm formatting and references match your style guide (APA/Chicago/MLA).
For an expanded checklist, use: The Ultimate Editing Checklist for Dissertations, Essays and Assignments: From Macro Structure to Microcopy.
Contact us for writing or proofreading assistance
If you need help polishing your dissertation, essay or assignment, MzansiWriters can assist. Contact us via the WhatsApp icon on the page, email info@mzansiwriters.co.za, or visit the Contact Us page in the main menu. We offer editing, proofreading and formatting services tailored to academic standards.
Additional resources on our site:
- Formatting Consistency and Style Guides: Streamline Editing for Dissertations, Essays and Assignments
- Using Track Changes and Collaborative Editing Workflows for Dissertations, Essays and Assignments
Follow these guidelines and your academic writing will be clearer, more professional and more persuasive. Good editing is the difference between good research and research that makes an impact.