Plagiarism and collusion

Please read these notes about plagiarism and collusion which apply to all assessed work, including essays, experimental results and computer code.

This document contains advice on the University's official definitions of plagiarism and collusion, how to reference your sources, when direct quotation is acceptable, and what action might be taken if you fail to abide by these guidelines.


During the course of your degree programme in this department, you will sometimes be asked to write essays or lab reports as part of the assessed work of a module. This will often involve reporting the work of others, for example in writing a review of the state of a research field or in explaining the background theory for an experiment. You must, however, ensure that the materials you prepare for submission would be accepted as your own original work. There are two principal reasons for this: firstly, the authors of the original material own that material (copyright), and using it as your own constitutes a form of theft; secondly, the person who is assessing your work is interested in your understanding of the ideas and information you report, and you can only demonstrate that understanding by using your own words.
Thus, the basic principle underlying the preparation of any piece of academic work is that the work submitted must be your own original work. Plagiarism and collusion are not allowed because they go against this principle.

Please note that the rules about plagiarism and collusion apply to all assessed work, including essays, experimental results and computer code.

What is plagiarism?

The following definitions of plagiarism and collusion are taken from the University's Teaching and Learning Support Unit, and represent the University's standard policy on this issue.

Plagiarism is passing off others' work as your own, whether intentionally or unintentionally, to your benefit. The work can include ideas, compositions, designs, images, computer code, and, of course, words. This list is not exhaustive. The benefit accrued could be, for example, an examination grade or the award of a research degree.

  • If a student submits a piece of work produced by others, or copied from another source, this is plagiarism.
  • If a student produces a piece of work which includes sections taken from other authors, this is plagiarism. The length of the copied section is not relevant, since any act of plagiarism offends against the general principle set out above. When copying sections from other authors it is not sufficient simply to list the source in the bibliography.
  • If a student paraphrases from another source without the appropriate attribution, as outlined in the section on referencing, this is plagiarism. Paraphrasing should use a student's own words to demonstrate an understanding and accurately convey the meaning of the original work, and should not merely reorder or change a few words or phrases of the existing text.
  • If a student copies from or resubmits his or her own previous work for another assignment, this is self-plagiarism, and is not acceptable.

Collusion is a form of plagiarism where two or more people work together to produce a piece of work all or part of which is then submitted by each of them as their own individual work.

  • If a student gets someone else to compose the whole or part of any piece of work, this is collusion.
  • If a student copies the whole or part of someone else's piece of work with the knowledge and consent of the latter, then this is collusion.
  • If a student allows another student to copy material, knowing that it will subsequently be presented as that student's own work, then this is collusion.
  • If two or more students work on an assignment together, produce an agreed piece of work and then copy it up for individual submission, then this is normally collusion. In group assignments such as group projects, some degree of collaboration may be acceptable, or even required: if it is not clear from the written instructions, students should seek the advice of the member of staff who set the assigned work regarding the acceptable limits of collaboration.

Both plagiarism and collusion are strictly forbidden. Students are warned that the piece of work affected may be given a grade of zero, which in some cases will entail failure in the examination for the relevant unit or research degree. The student may also be referred to the Discipline Committee.

Referencing sources

If you use information you obtained from another source, for example a textbook, paper, lecture or website, you must acknowledge that source. The usual practice in modern scientific papers is as follows:

  • At the point in the paper where information from a particular source is used, a marker is inserted in the text: this is normally either a number or the name of the first author of the source (see below).
  • The source is then given in a list of references at the end of the paper.

(In very old papers, such as those you might have consulted for a History of Astronomy essay, it was conventional to put the references in as footnotes. This is no longer standard practice, and you should not use this method.)

There are two standard styles of citing references:

Using name of first author:

  • In text: "All elements heavier than lithium are created by fusion or neutron capture in stellar interiors(Burbidge et al. 1957)"
  • At end: EM Burbidge, GR Burbidge, WA Fowler and F Hoyle (1957) Rev. Mod. Phys. 29 547-650.

    References listed in alphabetical order of first author

Using numerical markers:

  • In text: "All elements heavier than lithium are created by fusion or neutron capture in stellar interiors[1]"
  • At end: [1] EM Burbidge, GR Burbidge, WA Fowler and F Hoyle (1957) Rev. Mod. Phys. 29 547-650.

    References listed in order of appearance in the text

The first of these is more common in astronomy papers, and has the advantage that you do not need to renumber every reference if you add one near the beginning of your essay; the second is standard in physics journals (sometimes the number is typeset as a superscript1 rather than in square brackets[1]).

Your citation should contain all the information the reader needs to find the document:

Journal papers:

  • authors' names (first author plus "et al." if there are more than 3), journal title, volume number, year of publication, page number of first page of paper


  • authors' names (first author plus "et al." if there are more than 3), book title, edition if there has been more than one edition, publisher's name, date of publication

Web sites:

  • authors' names (first author plus "et al." if there are more than 3), title of site, full URL

You asked someone and they told you:

  • person's name, "private communication", date (e.g. Dr T. Richardson, private communication, December 2002)

If you use the same source more than once, do not repeat it in the list of references: just use the number you have previously defined (in other words, you can use the marker [1] as many times as you refer to the paper numbered [1] in your list of references).

Citing a source entitles you to use the information contained in that source. It does not entitle you to use the source's exact words, either verbatim or slightly rearranged.

Direct quotations

If you use a source's exact words, you must enclose them in quotation marks, set them off in a different type style or with different margins, or in some other way clearly distinguish them from your own work. Direct quotations should form only a very small part of the submitted material (say, <5%).

When can you use a direct quote?

If you are quoting a formal definition.

  • The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom."
    NIST Reference on Constants, Units and Uncertainty,

If you are quoting an opinion (with which you do not necessarily agree).

  • Freeman and Bland-Hawthorn (2002) argue that "detailed high-resolution abundance studies of large samples of galactic stars will be crucial for the future" of studies of galaxy formation and evolution
    Ken Freeman and Joss Bland-Hawthorn (2002), Annual Review of Astronomy and Astrophysics, 40, 487

If you are genuinely reporting direct speech, e.g. the reactions of someone actually involved.

  • Morgan remembers the mapping of the Galaxy's spiral arms as "a jewel all the way. It was absolutely perfect."
    William Morgan, quoted in Ken Croswell, The Alchemy of the Heavens (Oxford University Press, 1996)

If you wish to comment on specific features of the author's writing style (for example, in writing a book review).

  • Although the translation of Einstein's book on Relativity is good, it does date from 1920, which accounts for the slightly archaic style: "the occupant of the carriage is not sensible of its motion".
    Einstein, Relativity (15th edition, 1954, reissued 2001, Routledge Classics), translated by R.W. Lawson; quotation from p63.

When should you not use a direct quote?

If you don't actually understand what you have read, and want to quote because you are afraid that if you try to use your own words you will get it wrong.

  • The whole point of writing reports is that you should understand the material you have read. If you do not understand something but believe it to be too important to miss out, consult your supervisor, or the module lecturer.

If you are convinced that your phrasing is much less satisfactory than the original.

  • This may well be true, but does not justify quotation! You are being assessed partly on your ability to write essays and reports in the correct scientific style, and attempting to disguise your problems in this area by excessive quotation is not acceptable (even if you acknowledge the quotations properly). This is why direct quotations should account for only a very small proportion of the submitted material.

    If you do have trouble with your written English, the English Language Teaching Centre's Writing Advisory Service may be able to help you.

If you are running close to the deadline, and haven't got time to think up your own words.

  • (No further comment required!)

Note that you should never avoid direct quotation by simply making minor alterations in the word order or punctuation of the original. This is most definitely plagiarism. If you decide to quote, then quote; if you cannot justify quoting, then use your own words.

What if you get caught?

If you submit some work for assessment, and the assessor feels that it has been plagiarised, he or she will normally bring the matter to the attention of the relevant Year Tutor (or the module lecturer if the assessed work is a component of a module). The Year Tutor will consider the evidence (usually the source document(s), with indications as to which parts of your work the assessor believes to be too close to the original) and decide what action should be taken.

If it is considered that the plagiarism is minor and is undertaken without intent to deceive (for example, a few sentences or a figure taken from a referenced source but not acknowledged as quotations), then the likely outcome is that your mark will be a few percent lower than it would otherwise have been, and the feedback form will draw your attention to the problem.

If the plagiarism is deemed serious but unintentional (for example, large sections of the report are close paraphrases of the original sources, but the sources are properly referenced and there are mitigating circumstances such as inexperience), you will be called in to discuss the matter. You may be given an opportunity to redo the work, but this is not guaranteed, especially in third or fourth year. You should expect a substantial mark penalty, depending on how much of the work is affected.

If there is serious plagiarism without mitigating circumstances (i.e. blatant disregard of the guidelines), you should expect a zero grade for the affected work, and a note on your student record.

If there is intent to deceive (the plagiarised source is not included in the list of references), or it is a repeat offence (i.e. you have been previously warned about plagiarism), you should expect a zero grade for the affected work and a report to the appropriate university disciplinary committee. In the worst case, this could result in expulsion from the university.

Dr S. Cartwright