Perfecting Sentence Structure in Your Thesis or Dissertation

Perfecting Sentence Structure in Your Thesis or Dissertation

Writing a thesis or dissertation places enormous demands on your academic communication skills. You are expected to explain complex material with precision, incorporate technical terminology, build persuasive arguments and present detailed data—often in a language that is not your first. Even students who write confidently in English for coursework often find that the level of linguistic sophistication required for a doctoral thesis is significantly higher.

Clear, well-crafted sentences are essential for conveying nuanced ideas and ensuring that supervisors, examiners and journal reviewers can understand and evaluate your work fairly. Yet many postgraduate writers struggle with sentence-level issues, especially when working with longer, more complex structures. Two of the most common problems are sentence fragments and fused (run-on) sentences. Both errors disrupt readability, weaken arguments and create an impression of careless writing.

This article explains how to identify and correct these issues, clarifies the roles of independent and dependent clauses and provides additional strategies for refining sentence structure across long academic documents. Mastering these principles will significantly enhance the clarity and professionalism of your thesis or dissertation.

1. Understanding Clauses: The Foundation of All Academic Sentences

Every English sentence is built from clauses. A strong grasp of clause types allows you to combine ideas effectively, avoid structural errors and convey your argument with precision.

1.1 Independent Clauses

An independent clause contains a subject and a verb and expresses a complete thought. It can stand alone as a sentence. For example:

She wrote her thesis last year.

Independent clauses are the backbone of academic prose. They deliver the core meaning of your argument and must be used correctly if you want your writing to be clear and authoritative.

1.2 Dependent Clauses

A dependent clause also contains a subject and a verb, but it does not express a complete thought. It relies on another clause to complete the meaning. For example:

As she wrote her thesis last year…

The reader immediately expects additional information: What happened as she wrote? Why is this detail relevant? Dependent clauses typically begin with dependent markers (also called subordinating conjunctions) such as because, although, before, when, while, if, since, after and as.

Understanding the difference between independent and dependent clauses is essential for constructing grammatically correct sentences—particularly when your prose becomes more complex.

2. Sentence Fragments: Incomplete Thoughts Presented as Sentences

A sentence fragment occurs when a dependent clause or other incomplete structure (e.g., a phrase) is punctuated as if it were a full sentence. Fragments often appear in early drafts when writers break long sentences into smaller ones but forget that some of those smaller parts cannot stand alone.

Consider this dependent clause:

Before I circulated the third questionnaire.

This fragment contains a dependent marker (before), which means it must be followed or preceded by an independent clause:

Before I circulated the third questionnaire, I transcribed the responses from the first two.

Notice the comma after the dependent clause when it comes first. If the independent clause comes first, the comma is often optional:

I transcribed the responses from the first two before I circulated the third questionnaire.

2.1 Why Sentence Fragments Are Problematic in Theses

Fragments interrupt the logical flow of your writing. In highly technical documents such as theses, fragments can confuse examiners because they obscure the relationships among key ideas. A thesis must be readable and logically precise; fragments undermine both clarity and authority.

2.2 How to Avoid and Fix Fragments

To avoid fragments:

• Identify dependent markers (because, before, as, although, when).
• Check whether each clause expresses a complete thought.
• Ensure every dependent clause is attached to a complete independent clause.

To fix fragments:

• Add a main clause to complete the meaning.
• Turn the fragment into a phrase within a larger sentence.
• Remove the dependent marker if your intention was to create an independent sentence.

3. Fused (Run-On) Sentences: Too Much Meaning Without Structural Support

A fused sentence (or run-on sentence) occurs when two independent clauses appear back-to-back with no punctuation or linking word. The result is grammatically incorrect and often confusing.

A classic example is:

I devised new criteria for the third questionnaire the sample size was reduced.

Because both parts express complete thoughts, they must be separated or connected correctly. Depending on the intended meaning, there are many solutions:

• Two separate sentences:
  I devised new criteria for the third questionnaire. The sample size was reduced.
• With a coordinating conjunction:
  I devised new criteria for the third questionnaire, and my supervisor suggested that the sample size be reduced.
• With contrast:
  I devised the new criteria for the third questionnaire, but my supervisor suggested that the sample size be reduced.
• With a prepositional phrase:
  I devised new criteria for the third questionnaire by reducing the sample size.
• With a semicolon and adverbial connector:
  I devised new criteria for the third questionnaire; as a result, the sample size was reduced.
• With a subordinating conjunction:
  I devised new criteria for the third questionnaire after my supervisor recommended that the sample size be reduced.

These revision options illustrate how grammar allows you to express different logical relationships—cause, contrast, sequence or result—simply by choosing the correct connector.

3.1 Why Run-On Sentences Harm Academic Writing

Run-on sentences overwhelm the reader and make your reasoning ambiguous. In a thesis, where precision is essential, unclear sentence boundaries can obscure your methodological steps, misrepresent your findings or weaken your argument. Reviewers may interpret run-ons as signs of rushed or careless writing.

3.2 How to Avoid Run-On Sentences

To eliminate run-ons:

• Use a period when two ideas are not closely related.
• Use a semicolon when the relationship is close but not dependent.
• Add coordinating conjunctions (and, but, or, so, yet, nor, for).
• Use subordinating conjunctions to show relationships (because, although, after, while).
• Break long chains of thought into manageable sentences.

4. Additional Strategies for Improving Sentence Structure in Theses

Beyond avoiding fragments and run-ons, thesis writers should master several broader strategies for building readable, academically sound sentences.

4.1 Prioritise Clarity Over Complexity

Many students mistakenly believe that academic writing must be extremely dense or complicated. In reality, clarity is the hallmark of strong scholarly prose. Use complex sentence structures when appropriate, but avoid long, multi-clause sentences that obscure your meaning.

A useful guideline: One sentence = one central idea. Complex arguments can span multiple sentences; forcing them into one long sentence usually harms clarity.

4.2 Use Transitions to Show Logical Flow

Transitions such as therefore, however, moreover, in contrast, consequently help readers move from one idea to the next. They support structure and guide interpretation.

For example:

• “The results were inconclusive; however, further testing revealed significant trends.”
• “The methodology was limited; therefore, additional validation is required.”

4.3 Maintain Grammatical Parallelism

Parallel structure improves rhythm and professionalism. Consider this flawed list:

The study aimed to measure accuracy, assessing reliability and how fast participants responded.

Revised version:

The study aimed to measure accuracy, assess reliability and examine response times.

Each item now uses a verb in the same form, improving balance and readability.

4.4 Be Consistent With Terminology and Tense

Academic writing requires linguistic consistency. Use the same terms throughout to refer to the same concepts. Additionally, use verb tenses purposefully:

• simple past for your methodology and findings,
• present tense for established knowledge,
• present perfect when referring to ongoing scholarly conversations.

4.5 Read Your Work Aloud

Reading aloud helps identify awkward phrasing, abrupt transitions and unclear logic. If a sentence is difficult to say, it is usually difficult to read.

4.6 Use Professional Proofreading When Needed

Even strong writers benefit from professional proofreading—particularly when writing in English as an additional language or when working with highly technical content. A proofreader can catch:

• grammar and punctuation issues,
• awkward or unclear phrasing,
• tense inconsistencies,
• formatting problems,
• structural weaknesses at sentence level.

Conclusion: Strong Sentences Support Strong Scholarship

Perfecting sentence structure is an essential part of writing a successful thesis or dissertation. Sentence fragments interrupt your meaning, while run-on sentences overwhelm readers and obscure your logic. By mastering the distinction between independent and dependent clauses, using punctuation correctly, and strategically combining clauses to express precise relationships, you can significantly improve the clarity and impact of your academic writing.

The techniques described in this article—revising iteratively, reading aloud, using transitions, maintaining parallel structure and seeking feedback—will help you produce polished, credible and professional prose. Ultimately, clear sentences lead to clear arguments, strong exam results and successful scholarly communication.