Plagiarism vs Self-Plagiarism
Plagiarism is using another person's words, ideas or data without proper credit. Self-plagiarism (text recycling) is reusing your own previously published words or data without disclosure. Both can mislead readers and editors, and journals use similarity-checking software to detect overlap.
Differences
| Feature | Plagiarism | Self-plagiarism |
|---|---|---|
| Source | Someone else's work | Your own earlier work |
| Core problem | Taking credit for others' work | Presenting old work as new, or breaching copyright and journal policy |
| Typical forms | Copying text, paraphrasing too closely, using ideas or data without credit | Reusing text or results from a previous paper without citing |
| Handling | May constitute misconduct | Judged by extent, intent, disclosure and journal policy |
What is usually acceptable
- Quoting with quotation marks and citation.
- Paraphrasing in your own words and citing the source.
- Reusing short, standard method descriptions with citation, if the journal permits; many journals discourage verbatim reuse of larger parts.
- Publishing an expanded version of a conference abstract with disclosure.
How to avoid both
- Take notes in your own words, and record sources.
- Quote precisely and cite.
- Cite your previous work and disclose overlap in the cover letter.
- Use a similarity checker, if available, before submission and review the matches critically.
- Do not use AI tools to paraphrase sources in a way that hides their origin; always verify and cite.
Illustrative example
Invented for teaching. A student copies a long definition from a review and changes a few words. Even with a citation, the text is too close. She rewrites it in her own words with an in-text citation. In another paper, she reuses her earlier Methods paragraph, cites the first paper and tells the editor about the overlap.
Common pitfalls
- Believing that changing a few words is paraphrasing.
- Assuming that your own words may be reused freely.
Key takeaways
- Credit sources and disclose reuse.
- Check journal policy and verify similarity reports.
References and further reading
- Committee on Publication Ethics (COPE): guidance and flowcharts. Link
- International Committee of Medical Journal Editors (ICMJE). Recommendations for the Conduct, Reporting, Editing, and Publication of Scholarly Work in Medical Journals. Link
- U.S. Office of Research Integrity. Definition of research misconduct. Link
Related reading
This page is general educational information about research methods. It is not medical, legal or regulatory advice; follow your institution's ethics board and your target journal's instructions.