Avoid Commonly Confused Words
Lesson 19 of 20 Thesis Editing Tips
From the Examiner’s Desk
“I frequently examine theses in which years of excellent research are obscured by weak writing.”
Many writing guides focus on grammar.
This lesson focuses on readability.
Its purpose is to help readers understand your ideas more quickly and with less effort.
As a PhD examiner and thesis editor, I often see theses containing words that are correctly spelled but used incorrectly.
These mistakes are particularly difficult to detect because spelling and grammar checkers usually do not identify them.
The result is writing that appears careless, even though the research itself may be excellent.
Learning to recognise commonly confused words is one of the simplest ways to improve the accuracy and professionalism of your writing.
Why These Words Cause Problems
Many English words look alike, sound alike or have related meanings.
Choosing the wrong word can subtly change the meaning of a sentence or make it sound unnatural.
These errors are especially common when English is a second or third language.
Fortunately, they are also easy to avoid once you know the differences.
Frequently Confused Word Pairs
Compared
with
vs Compared
to
Use compared with when examining similarities or differences between similar things.
Use compared to when making an analogy between different things.
Examples:
✅ Male rats were compared with female rats.
✅ She compared the human brain to a computer.
Concentration vs Level
Use concentration when describing the amount of a substance in a solution or mixture.
Use level when referring to the amount of something measured in the body or to a position or ranking.
Examples:
✅ The glucose concentration was 5 mmol/L.
✅ The patient’s cholesterol level was elevated.
Different
from
In formal academic writing, different from is generally preferred.
Example:
✅ The experimental group was different from the control group.
Although different than occurs in some varieties of English, particularly in North America, many universities and journals prefer different from in formal writing.
Discrete vs Discreet
These two words are often confused because they sound similar.
Discrete means separate or distinct.
Discreet means careful or tactful.
Examples:
✅ The analysis consisted of three discrete stages.
✅ The researcher remained discreet during the interview.
Principal vs Principle
Principal usually refers to a person in charge or something that is primary.
Principle refers to a rule, belief or scientific law.
Examples:
✅ The principal investigator supervised the project.
✅ The experiment was based on an established scientific principle.
Other Commonly Confused Words
Many postgraduate students also confuse:
affect (usually a verb)
effect (usually a noun)
accept (receive)
except (excluding)
advice (noun)
advise (verb)
complement (complete or enhance)
compliment (praise)
These small differences can completely change the meaning of a sentence.
💬 WhatsApp with Dr Anastasia Apostolides (reasonable hours)
Why Examiners Notice These Errors
Unlike spelling mistakes, these words are spelled correctly.
That means automated spelling checkers rarely detect them.
Experienced examiners, however, recognise incorrect usage immediately.
Repeated mistakes suggest that the thesis has not been carefully proofread.
Using the correct word demonstrates precision and attention to detail.
Practical Editing Strategies
Before submitting your thesis:
• Create a list of word pairs that you commonly confuse.
• Pay particular attention to technical terms within your discipline.
• Read your work slowly rather than relying on spelling software.
• When in doubt, consult a reputable dictionary or your university’s style guide.
A few minutes spent checking word choice can significantly improve the quality of your writing.
Quick Editing Checklist
Before submitting your thesis, ask yourself:
✓ Have I chosen the correct word rather than simply the correctly spelled word?
✓ Have I checked commonly confused word pairs?
✓ Does the word fit the context?
✓ Have I verified unfamiliar terms?
✓ Would another reader interpret my meaning correctly?
Key Takeaway
Accuracy in academic writing extends beyond spelling.
Choosing the correct word demonstrates precision, attention to detail and respect for your reader.
Small differences in wording often make a significant difference to the clarity of your thesis.
The right word does more than avoid mistakes.
It communicates your ideas with confidence and precision.
Need Professional Thesis Editing?
If you would like an experienced PhD examiner to review your thesis before submission, I’d be happy to help.
Whether you need a complete thesis edit, advice on improving clarity or feedback on a proposal, feel free to get in touch.
Dr Anastasia Apostolides
PhD Examiner • Thesis Editor • Proposal & Academic Consultant
Helping Master’s, MBA, DBA and PhD students write with clarity and confidence.
💬 WhatsApp with Dr Anastasia Apostolides (reasonable hours)
📧 Email: info@uedit.org
📍 uedit.org
Continue Learning
This article is part of the 20 Thesis Editing Tips series.
Continue to the final lesson or explore the complete collection of free thesis resources to strengthen every stage of your academic writing.