Self-citation and self-plagiarism
Referencing your own previously published work is known as self-citation. It is important to give citations when ideas, data, etc have been discussed in your previous publications. Correct self-citation conveys the level of originality in a publication accurately and enables readers to understand the development of ideas over time.
Academic publication takes many different forms. Researchers will often write up their findings for more than one publication, for example in a thesis and a journal article, or a blog post and book chapter. This is not necessarily a problem, but researchers need to consider their choices carefully. Reusing text word-for-word in multiple pieces of writing is known as self-plagiarism. This may seem like a contradiction because a researcher cannot ‘steal’ their own ideas. Citations, however, are not just about giving credit for ideas, they also enable readers to trace the development of an idea over time and honestly represent the originality in a piece of writing.
Norms about what is an acceptable way of acknowledging that you have previously published research have changed significantly, even in the past decade. It is important that researchers are aware of what is considered good practice in their disciplines. A supervisor, mentor, or peers may be able to offer advice.
There is no definitive rule about when it is acceptable for a researcher to re-use text word-for-word. You should consider this carefully on a case-by-case basis taking into consideration:
- the norms of your discipline
- the conventions of the genre you are writing in (e.g. journal article, blog, thesis etc)
- the expectations of editors, publishers, examiners, and readers
- copyright regulations and authorship.
There are three key questions you should ask yourself:
- does the piece of writing represent its own level of originality accurately?
- is that level of originality appropriate to the type of publication?
- who has the right – ethically (authorship) and legally (copyright) – to reproduce?
Many journals have a specific policy about reusing text, such as from a PhD thesis, in the ‘Instructions to Authors’ section (or similar) of their webpage. You should contact editorial staff of any publication to clarify any questions before submitting.
The La Trobe guide, Interpreting iThenticate Reports: a Guide for Researchers [DOC 711KB], includes a discussion of the expectations of different genres of writing, and suggestions on how iThenticate can help manage self-citation and avoid self-plagiarism.
Discipline approaches to self-plagiarism
Some style guides have a statement and/or guidelines relating to self-citation or self-plagiarism which may be helpful:
From the MLA Style Manual and Guide to Scholarly Publication. Modern Language Association of America: New York, 2008. Third edition. pp. 166-167.(Humanities):
'Whereas reprinting one’s published work, such as having a journal article appear in a subsequent book of essays, is professionally acceptable […] professionals generally disapprove if previously published work is reissued, whether verbatim or slightly revised, under another title or in some other manner that gives the impression it is a new work. Although not the same as plagiarizing someone else’s writing, self-plagiarism is another type of unethical activity. If your current work draws on your own previously published work, you must give full bibliographic information about the earlier publication.'
From the Publication Manual of the American Psychological Association. American Psychological Association: Washington, D.C., 2010. Sixth edition. p. 16.(Social Sciences):
'Just as researchers do not present the work of others as their own (plagiarism), they do not present their own previously published work as new scholarship (self-plagiarism). There are, however, limited circumstances […] under which authors may wish to duplicate without attribution (citation) their previously used words, feeling that extensive self-referencing is undesirable or awkward. […] The general view is that the core of the new document must constitute an original contribution to knowledge, and only the amount of previously published material necessary to understand that contribution should be included, primarily in the discussion of theory and methodology.'
Reusing published material in Masters and PhD theses
Including previously published material (text, ideas, data, even a whole publication) in a Master's or PhD thesis is very common. You should consider the key questions about self-citation above when doing so, and ensure compliance with La Trobe requirements. Every thesis should clearly state what material has been previously published and where.
If you paraphrase or quote short sections of your own text, you should reference it as you would the work of another scholar.
You may insert a whole publication or publications into your thesis if appropriate to the argument and structure. You should discuss this with a supervisor as early as possible. If a thesis chapter is substantially based on research reported in a previous publication, full citation details should be included in the preface or each relevant chapter. The full reference should also appear in the bibliography of the thesis.
Publications may form the majority of your thesis. In this case framing material should also be included to show how the different publications are thematically linked.
You must have written permission from the copyright holder to include previously published material. In many cases the publisher, not the author, is the copyright holder and permission must be sought.
If a co-authored publication is included in a thesis you must:
- have made a leading and significant contribution to the publication
- provide details of your contribution to each publication in the thesis
- provide verification of your contribution from co-authors.
The Schedule for Presentation of Theses for Higher Degree by Research offers a guide to what you must do if previous publications are included in your thesis.
For examples of La Trobe theses written to the highest standard see the Nancy Millis Award page.