How We Screen for Plagiarism

Standard definitions describe plagiarism as the act of presenting someone else’s work as one’s own. In academic writing, a common example is copying text from a source into one’s own work without quotation marks and proper attribution. Plagiarism, however, is not limited to wording. It can also mean using someone else’s ideas, concepts, figures/tables, data or structure without appropriate acknowledgement. Moreover, in the case of self-plagiarism, it refers to the act of presenting one’s own previous work as if it were new.

When you submit your PhD thesis in Pure, it is received by the University Library’s PhD support team. The thesis is then uploaded to SDU’s plagiarism screening software as part of the mandatory screening process.

You can submit your PhD thesis in Pure right up until your formal submission deadline, even though the thesis is not formally submitted until it has completed the plagiarism screening, which may take up to two working days.

The screening software checks the thesis for textual similarity and generates a so-called similarity report. This report highlights passages that are identical, or near-identical, to previously published texts, including journal articles, books, theses and online material.

Importantly, the screening is not an automated decision-making process. A member of the PhD support team always reviews the report manually. During this review, highlighted passages are assessed to determine whether they consist of correctly cited quotations, legitimate forms of text reuse (see below), missing or incomplete references or perhaps problematic reuse of previously published material, such as the author’s own work.

Based on this assessment, the screening results in a colour-coded conclusion (green, yellow or red), which determines the next steps in the submission process. Since the PhD thesis is not formally submitted until it has passed the plagiarism screening, it is important to monitor your email after uploading your thesis in Pure in case revisions or clarifications are required.

Self-plagiarism is by far the most common form of plagiarism detected in SDU’s plagiarism screening. This often occurs because PhD students are not aware that they cannot simply reuse text from their published articles in other parts of their PhD thesis.

In most cases, verbatim reuse of previously published text must be clearly signalled using quotation marks, italics, indentation or similar formatting (for exceptions, see “Acceptable Text-Recycling” below). Here are a few tips to help you avoid self-plagiarism:

• If a chapter of your PhD thesis is identical to a previously published article, this should be stated clearly at the beginning of the chapter (unless the published article has been inserted in the publisher’s layout). 
  Example: “This chapter is identical to the published version of: [Full citation]. The text appears here with permission from the publisher.”
  
  
• If a subsection of a chapter is identical to previously published text, this should be stated clearly at the beginning of that subsection. 
  Example: “Section 3.2 is identical to material previously published in: [Full citation].”
  
  
• If a chapter is nearly identical to a previous publication, but text has been added or removed, this should be stated at the beginning of the chapter.
  Example: “This chapter is adapted from: [Full citation]. The present version includes additional analysis in Sections 4.3 and 4.4. Minor editorial adjustments have been made.”
  
  
• If a chapter is partially based on a previous publication, identical passages should be clearly shown using quotation marks, italics or – for example – a different font. The method used to indicate text reuse should be stated at the beginning of the relevant chapter or subsection.
  Example: “This chapter incorporates passages from: [Full citation]. Verbatim text from the original publication is indicated using the Calibri font rather than the standard Times New Roman. All other material is newly written for this thesis.”
  
  
• NB: It is not sufficient to merely write: “The following chapter is based on [Full citation]” without explaining the changes made to the original publication. The reader must be able to see the exact degree of text reuse.

These guidelines are based on recent statements in the yearly reports on questionable research practices published by the Danish Board on Research Misconduct and are intended to promote transparency and good academic practice in PhD theses.

Although you should generally avoid copy-pasting text from your previously published work into your PhD thesis, there are exceptions where text-recycling can be both legitimate and suitable. The three main examples are:

• Definitions: Definitions are meant to be precise, and altering the wording can change the meaning. Consequently, in most academic fields it is acceptable to reuse definitions – e.g. of physical laws, medical conditions, judicial concepts or technical classifications – without quotation marks, provided that proper attribution is given.
  
  
• Methodology: As with definitions, scientific methods often need to be described in a precise, technical and unambiguous manner, which can make rephrasing difficult without compromising accuracy. Thus, when describing methods – e.g. experimental procedures, laboratory protocols or data collection techniques – it is generally legitimate to reuse those passages verbatim, as long as the original source is referenced.
  
  
• Lists: In some academic fields it is common to present long lists of items – e.g. symptoms or side effects when describing a disease or a form of medication. In such cases, it is perfectly acceptable to reproduce such lists verbatim, as long as sources are properly referenced.

There are other, less common, cases in which reusing previously published text without quotation marks is acceptable. As a general rule, however, any verbatim reuse should be clearly signalled in your PhD thesis.

With the emergence of generative AI, it has become possible to produce text without having written it oneself. In this context, it is important to remember that, as the author of your PhD thesis, you are fully responsible for any form of plagiarism contained in the thesis, even if the problematic text was generated by an AI tool. This is especially relevant because AI tools sometimes reproduce phrases, sentences or structures from existing texts without attribution.

In consequence, it is crucial that you disclose any use of AI. It is acceptable to use AI for writing assistance, grammar checking, language polishing or similar support, as long as you include a short “Declaration on the Use of AI” at the beginning of your PhD dissertation (e.g. after the Acknowledgements section).

• Example: “This dissertation has made limited use of Microsoft Copilot (version XX) for language editing and grammar checking. All ideas, analyses and interpretations are my own, and I take full responsibility for the accuracy and originality of the content.”