Similarity reports are now a routine part of academic writing and thesis submission in many institutions. A similarity percentage can help identify passages that require closer examination, but the percentage itself does not determine whether a thesis contains plagiarism or inappropriate source use.
A doctoral thesis inevitably contains terminology, technical expressions, established definitions, methodological descriptions and properly cited material that may correspond with other published sources. Conversely, a thesis can have a relatively low similarity percentage while still containing poorly attributed or improperly reused material.
The appropriate objective is therefore not to achieve a particular similarity score. The objective is to ensure that the thesis demonstrates independent scholarly expression, appropriate synthesis of sources, accurate attribution and responsible use of existing academic material.
What Does Similarity Mean in a Thesis?
A similarity-checking system identifies text that corresponds with material contained in its comparison database. The resulting report indicates textual overlap; it does not independently determine whether that overlap constitutes plagiarism.
Similarity may arise from several legitimate sources, including correctly quoted material, technical terminology, commonly used academic expressions, titles and headings, references and bibliographic information, standard methodological descriptions, institutional or regulatory terminology and appropriately cited definitions. The meaning of a similarity result therefore depends on the context of the matched passage. Therefore, a similarity report should be interpreted rather than treated as a simple pass-or-fail measure.
Understand Why Similarity Has Occurred
Examine the actual matched passages before revising a thesis.
Ask:
- Is the material directly quoted?
- Has the original source been cited?
- Is the wording unnecessarily close to the source?
- Is the passage describing an established concept?
- Has a standard methodological procedure been reported?
- Does the overlap occur in references, headings or other unavoidable sections?
- Has the same wording been reused from an earlier publication or document?
This assessment should take place before any rewriting. A high similarity percentage does not automatically indicate academic misconduct and a low percentage does not automatically establish originality.
Strengthen Source Synthesis
One of the most effective ways to improve originality in a literature review is to move from source-by-source reporting to synthesis.
A weak literature review may follow this pattern: Author A stated X. Author B stated Y. Author C reported Z. Although each source may be cited correctly, the paragraph remains largely a sequence of individual summaries. A stronger approach identifies relationships among studies: Existing studies indicate that X is influenced by several related factors, although the strength and direction of these relationships vary across contexts. The discussion can then explain how different studies support, challenge or extend this broader interpretation. This approach reduces unnecessary dependence on the sentence structure of individual sources and strengthens the analytical quality of the literature review.
Paraphrase by Reconstructing the Meaning
Paraphrasing does not mean replacing individual words with synonyms. A proper paraphrase requires understanding the source and expressing its meaning independently. A useful process is: Read → Understand → Set the source aside → Reconstruct the idea → Compare with the source → Cite. The rewritten passage should reflect the researcher’s understanding of the source rather than reproduce its sentence structure. Changing a few words while retaining the original syntax and sequence of ideas can still result in inappropriate textual overlap.
Avoid Patchwriting
Patchwriting occurs when a source’s wording or sentence structure is retained while selected words are changed. This is particularly common when writing literature reviews quickly or when working with highly technical sources. For example, replacing several nouns and adjectives in a published sentence does not necessarily produce an independent paraphrase. The better approach is to understand the underlying argument and reconstruct the sentence around the intended point. Citation remains necessary even when the wording has been substantially changed.
Use Direct Quotations Selectively
Direct quotations should be used when the exact wording is important. Examples may include formal definitions, legal or regulatory language, particularly significant statements and wording that requires precise preservation. Long quotations should not be used simply because rewriting the passage is difficult. If a direct quotation is appropriate, then quotation formatting and citation should follow the required referencing style.
Develop an Analytical Literature Review
An ideal literature review does more than demonstrate that relevant studies have been read. It should examine areas of agreement, areas of disagreement, methodological differences, theoretical perspectives, contextual differences, limitations in previous research and unresolved questions. For example, instead of describing ten studies independently, the literature can be organised around a theme and then compared critically. This strengthens the researcher’s own analytical voice while maintaining appropriate attribution to the literature.
Distinguish Common Knowledge from Source-Specific Claims
Not every sentence requires a citation, but source-specific claims generally do. Particular care is required for statistics, empirical findings, theoretical propositions, definitions, historical claims, distinctive arguments and models and frameworks. When uncertain, it is better to verify the original source rather than assuming a claim is common knowledge.
Review Previously Published or Submitted Work
Researchers sometimes reuse material from conference papers, journal articles, dissertations, research proposals, institutional reports and earlier academic assignments. This can create text overlap even when the material was originally written by the researcher. Such reuse should be reviewed carefully because institutional policies differ regarding self-plagiarism and text recycling. Previously published material may also be subject to copyright restrictions. The appropriate approach is to follow the university’s academic-integrity and publication requirements.
Check Citations and References
Similarity reduction should never involve removing citations simply to reduce matched text. A better approach is to check whether: every source-specific claim is appropriately cited; in-text citations correspond to the reference list; references are complete; quotations are clearly identified; paraphrases genuinely represent the source; secondary citations are used appropriately; and sources have been represented accurately. Scholarly context and proper citation matter more than the numerical similarity score.
Pay Attention to the Literature Review
The literature review often contains substantial textual overlap because it necessarily discusses established research. The solution is not to remove references or avoid discussing important studies. Instead, group → compare → critique → synthesise → identify the gap. For example, studies can be grouped according to theoretical perspective, population, methodology, geographical setting or findings. This produces a more scholarly literature review and reduces dependence on individual source wording.
Review the Methodology Carefully
Methodology chapters require particular judgement. Some methodological terminology and procedural descriptions are necessarily standardised. Excessive rewriting of technical terminology can actually reduce clarity. However, source-specific methodological explanations should still be appropriately attributed. The objective is to describe the actual procedure used in the study accurately rather than reproduce a published methodology verbatim. If a standard scale, instrument or established procedure is used, then the relevant source should be cited.
Do Not Manipulate the Similarity Report
A similarity report should be used as a diagnostic tool. It should not become a target that encourages artificial rewriting. Avoid practices such as: changing words without understanding the passage; deliberately introducing awkward wording; replacing standard terminology unnecessarily; removing legitimate citations; altering technical terms solely to change matches; inserting irrelevant material; and manipulating formatting to affect detection. Such practices can reduce readability without improving academic originality.
Review the Thesis Section-by-Section
A large thesis is easier to improve when examined systematically. The following is a practical sequence:
Stage 1: Introduction
Check definitions, background claims, statistics and statements derived from sources.
Stage 2: Literature Review
Focus on paraphrasing, synthesis, critical analysis and source attribution.
Stage 3: Methodology
Check source-specific descriptions, instruments, procedures and methodological references.
Stage 4: Results
Ensure that findings are reported as generated by the study and that external claims are clearly distinguished.
Stage 5: Discussion
Check how previous literature is paraphrased and integrated with the study’s findings.
Stage 6: Conclusion
Ensure that the final synthesis reflects the thesis without introducing unattributed material.
Compare the Revised Passage with the Original Source
After paraphrasing an important passage, compare it with the source. Check sentence structure, sequence of ideas, distinctive terminology, examples, argument structure and overall expression. The purpose is not to make the passage look different merely for the sake of difference. The purpose is to confirm that the wording genuinely represents an independent expression of the cited idea.
Preserve the Researcher’s Academic Voice
A doctoral thesis should not read like a collection of disconnected source summaries. The researcher’s academic voice becomes visible through synthesis, critical evaluation, interpretation, comparison, logical transitions, explanation of relevance and connection with the research problem. This is one reason why similarity reduction should be treated as part of academic writing improvement, rather than as a separate technical exercise.
Similarity versus Academic Integrity
| Issue | Appropriate approach |
|---|---|
| Similar wording | Examine the matched passage |
| Direct quotation | Use quotation conventions and citation |
| Paraphrasing | Reconstruct the meaning independently |
| Literature review | Synthesise and critically compare sources |
| Technical terminology | Retain accurate terminology where necessary |
| Previous publications | Check text-reuse and copyright requirements |
| Citations | Preserve appropriate attribution |
| Similarity percentage | Interpret in context |
| Academic integrity | Follow institutional requirements |
Common Mistakes
Several approaches can create problems:
Changing individual words: Synonym substitution is not the same as genuine paraphrasing.
Removing citations: This may reduce visible attribution while creating a more serious academic-integrity problem.
Over-paraphrasing technical terminology: Standard terminology may need to remain unchanged for accuracy.
Writing source-by-source literature reviews: This can make the thesis overly dependent on individual studies.
Ignoring self-reuse: Previously written material can also produce substantial overlap.
Treating the percentage as the only objective: A numerical score cannot replace academic judgement.
A Practical Revision Workflow
A useful workflow is:
- Generate or obtain the similarity report.
- Identify substantial or meaningful matches.
- Examine the original source.
- Classify the match as legitimate, appropriately quoted, appropriately paraphrased or requiring revision.
- Rewrite problematic passages by reconstructing the underlying meaning.
- Check the citation.
- Review the surrounding paragraph for synthesis and analytical coherence.
- Recheck the revised section for accuracy and readability.
- Conduct a final academic-integrity review.
This approach addresses the underlying writing issue rather than attempting to change a numerical score.
Final Checklist
Before submitting the thesis, check that:
- Source-specific claims are appropriately cited.
- Direct quotations are clearly identified.
- Paraphrased material is independently expressed.
- Patchwriting has been removed.
- The literature review demonstrates synthesis.
- The researcher’s analytical voice is evident.
- Methodological descriptions accurately represent the study.
- Previously published material has been reviewed for text reuse.
- References are complete and consistent.
- Technical terminology has not been changed unnecessarily.
- Similarity matches have been interpreted in context.
- No artificial wording has been introduced merely to reduce similarity.
- Institutional academic-integrity requirements have been followed.
Conclusion
Reducing similarity in academic and scientific writing should not be treated as a competition to achieve the lowest possible percentage. The more meaningful objective is to produce a thesis in which ideas are properly attributed, sources are critically synthesised and the researcher’s own scholarly expression is clear. An ideal thesis demonstrates originality through its research problem, analysis, interpretation, synthesis and contribution, and not merely through a low similarity score. Similarity checking can identify passages that deserve attention, but the final responsibility is to ensure that the thesis meets the academic, ethical and institutional standards applicable to the doctoral research.
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