I included some results in my thesis that some other PhD students included in theirs. Is this plagiarism?

Question

I would like to ask you a question about my PhD thesis, which has already been defended.

Part of my results were obtained in a university in another country. During my work, two of the PhD students there helped me and they have included these results in their theses. The problem is that I have also included these results in my PhD thesis, which was defended after theirs.

These results (included in my thesis, part of them in the thesis of one of the students and the other part in the thesis of the other student) are included in two publications. I am the first author of both of them, but I am given as equally contributed with one of the other PhD students in one of the paper and with the other PhD student in the other paper.

Do you think that I can be accused in plagiarism or be in authorship conflict?

Answer 1

You should cite the other publications, your authorship involvement and your noted contribution status.

You should also note that you are presenting the complete result set while the cited publications each contain a part thereof. You should informally notify the other authors of your intentions - this may not change your course of action but it would be useful to know that they don't intend to contest any of your work.

Answer 2

Most PhD theses I have seen so far included a sentence along the lines of the following somewhere:

This thesis contains material already published in the following publications: …

This applies to compilation theses as well as to monographs. My faculty’s PhD rules require such a sentence.

• If your thesis does not contain such a sentence, you have problems with self-plagiarism anyway.

• If your thesis does contain such a sentence, you properly informed the reader about the fact that those results were published elsewhere and reasonable accusations of plagiarism should not happen.

With respect to authorship conflicts, your PhD guidelines probably require that you contributed to all presented results to a certain extent or, if applicable, explicitly say to which results you did not comply to this extent. The latter is for example relevant if you have to present somebody else’s part of a colaborative work as a prerequisite for your work or in a compilation thesis. You have to decide yourself whether you adhered to this.

Answer 3

You should find out your school's policy. In addition to citing the previous work, you may need to fill out some additional paperwork. If I remember correctly, at my school using previously published results required written permission of the advisor and the journal, while using cowritten results required written permission from the coauthors.

Answer 4

If you haven't cited the other two theses, you would be committing plagiarism. You might not really be "accused" of plagiarism if you are just circulating your thesis internally and not publishing it as a book or parts of it as a journal paper. However, whether or not you are accused, you should follow academic best practices and cite the other two theses.