Dear Nicholas,

A very qood and important question indeed. I believe that we should be able to use our own work and we should not be forced to paraphrase our own work, however it seem that there is a the controversy about self-plagiarism Many scientists and publishers argue that it’s unavoidable for scientists to re-use portions of their own text (not images or data, of course) from previous papers, and that doing so may even be good practice. However, others disagree, including many journal editors—who have retracted published papers in response.

The following blog from the American scientist presents a case:

When Is Self-Plagiarism OK?

from the Scientist (Registration Required)

When Robert Barbato of the E. Philip Saunders College of Business at Rochester Institute of Technology (RIT) heard he was being accused of plagiarizing his own work, he was a bit surprised. "I can't plagiarize myself -- those are my own words," he said.

And he is not alone in his views. Some scientists and publishers argue that it's "unavoidable" for scientists to re-use portions of their own text (not images or data, of course) from previous papers, and doing so may even be good practice. But others disagree, including many journals -- who have retracted papers in response.

"There are many ways you can say the same thing even when it comes to very technical language," said Miguel Roig of St. John's University, who has written extensively about plagiarism in academic literature. "It's a matter of what some have labeled poor scholarly etiquette."

Using common phraseology is no sin. In fact, in the scientific and technical areas, it is a waste of time to try to say the same thing in different ways, because it confuses the reader. My rule of thumb is that if a phrase or even a full sentence has more than 10 entries on a Google search, then that phrase or sentence is "Common knowledge" and need not be cited. E.g., "napoleon died on st helena" Avoid paraphrasing as "The Emperor passed away on a tropical island of volcanic origin in the South Atlantic Ocean."!   

Dear Nicholas,

A very qood and important question indeed. I believe that we should be able to use our own work and we should not be forced to paraphrase our own work, however it seem that there is a the controversy about self-plagiarism Many scientists and publishers argue that it’s unavoidable for scientists to re-use portions of their own text (not images or data, of course) from previous papers, and that doing so may even be good practice. However, others disagree, including many journal editors—who have retracted published papers in response.

The following blog from the American scientist presents a case:

When Is Self-Plagiarism OK?

from the Scientist (Registration Required)

When Robert Barbato of the E. Philip Saunders College of Business at Rochester Institute of Technology (RIT) heard he was being accused of plagiarizing his own work, he was a bit surprised. "I can't plagiarize myself -- those are my own words," he said.

And he is not alone in his views. Some scientists and publishers argue that it's "unavoidable" for scientists to re-use portions of their own text (not images or data, of course) from previous papers, and doing so may even be good practice. But others disagree, including many journals -- who have retracted papers in response.

"There are many ways you can say the same thing even when it comes to very technical language," said Miguel Roig of St. John's University, who has written extensively about plagiarism in academic literature. "It's a matter of what some have labeled poor scholarly etiquette."

Ian-Behrouz: The system says you have commented, but there is nothing showing yet at this end .... I will reply when the 'glitch' gets sorted  ;-)

One trouble is that there is really only one way to say things best, and we should always use that formulation, because it is the one that the reader best understands.

Another trouble is that we are so immersed in our own work (and prior to today's powerful software we had no way of telling for sure whether we had used that thought before).

I do not know offhand where I first said "Avoiding plagiarism is easy -- just quote the source", but that is part of me, wearing my lecturer's cap.

Ok - back in business:

I agree that it is a bit pointless to become 'pc' about paraphrasing what is general information.  That said, many of the foundational things I am talking about will not yet appear 10 times on Google (does that mean I am producing original work!!).  I think that if you are not re-selling a previously published work, if the main theme is different & if the bits you go over are not a reference to a specific outcome of some previous study, then there is no problem.

Intent is a key issue I think - if you are not trying to re-sell or steal, then restating some important facts is ok (until they become common knowledge). When you're writing it though, it seems a bit ... repetitive.

Be interesting to see if someone has strong views on the subject  ;-)

Not everybody reads all your papers, so they will not be bored by repetitive phrases.

In the Humanities, when writing an article, we cite previous criticism at the beginning and move on from there to discuss our new information. There is no harm in citing oneself at the beginning and summarizing one´s previous findings before continuing onward, taking care not to mention one´s own name too often in the new article. Otherwise the more recently published piece will sound "old hat," solipsistic.

This question is interesting against our technological background. First, the computer helped list and find academic publications, then the number of publications by a given person started to be computed, along with impact factor for journals and individual "productivity " human index and the like for researchers.

The notion of "self plagiarism" is a consequence of such counting fever. It is indeed computed by checking similar (long) strings of characters in papers. However, the percentage of repeated strings in sentences or paragraphs is not set to zero, for a paper to be judged as sound when looking for plagiarism. Every one writes very similar formulae to introduce the plan and results.

On the question of how much should be repeated in articles for the human eye, I also had problems, even before the question was technically raised. If exploring a new issue, or elaborating a new method, the problem is indeed difficult. As an academic writer, I always found myself between the bark and the tree. In fact reviewers' criticism pointed out the lack of explanation or the redundancy of explanation, sometimes both.

As a reviewer, I do prefer a summary of what was previously published, although redundant when you follow someone, because the writers do not always keep the same aspects of their findings in mind as they progress.

On either side, however, explanations do take some place while the number of allowed pages becomes smaller and smaller… at least in my field. We are condemned to very sketchy explanations, I'm afraid. In the end, the chances of an original research to be overlooked are probably higher.

To balance this pessimistic view, I feel the possibility to add extra material online might come handy to provide better explanations. It is used in medicine, but this usage could be extended.

Redundancy & 'self' are good points.  It comes across a bit Gilderoy Lockhart to do the 'for further information ... see my published works'  thing  ;-)  I think it is possible to reduce coverage as work becomes more familiar, or as it becomes more focused.  For the foundational stuff though, a couple of paragraphs are always going to be setting the scene & context.  I have just dealt with a journal that gives extra on-line space for additional material (healthcare education), & I hope it becomes more widespread.

The counting & plagiarism thing is also interesting.  Obviously, plagiarism is clearly unethical, but we see frequent cases of people stealing the work of others (& this is probably the tip of the ice berg). Many will call it black & white, but I think the key issue of self-plagiarism is not necessarily the number of repeated strings, but the intent with which they are used.  If you are trying to re-sell work as new, then this is wrong, but if you are simply providing background information, then as Ian said, I don't know how far it is reasonable to go, paraphrasing basic information (of your own).  As a writer, I hope I will use logic & common sense.

I would agree, there is no clear and straight line. You are right, it's not about amount and percentage, it's about the intent. If you are repeating parts of your previous publications because you haven't actually so much new to say, that's self-plagiarism. But if your repetition is the solid ground for the new findings presentation, it is just concerned as any other citation.

Self-plagiarism is in fact a misnomer.  It is in fact academic misconduct or dishonesty as you can't plagiarise your self.  If you use large chunks of previous works of yours, e.g. conference papers, articles, chapters,etc., then you need to reference those just as you would with anyone else's works you use. 

Denise:  many would disagree with you about being not being able to plagiarise yourself (e.g. Google Scholar will give >59k results on the topic).  'Large chunks' implies re-selling the main content as new, but I am talking about repeating a relatively small amount of background content (non-verbatim), as supporting content for a new main topic.  I have also started a question as to what we mean by 'published', so we have to work out how the work was first presented & if we are misusing it  ( https://www.researchgate.net/post/When_is_a_conference_presentation_legaly_viewed_as_published?_tpcectx=profile_questions )

As I said above, I think intent is a key issue, but of course, if we are referring to our own work, we should cite it as you describe.  If we are loosely paraphrasing some supporting detail however, it is desirable not to self-cite.

Yes, I agree that if it more general information or common knowledge, it is not necessary to cite.  The term self-plagiarism has been used a lot on the internet, but strictly speaking it is academic misconduct/dishonesty, which at many tertiary institutions falls within the ambit of their Plagiarism policies. 

I think an important factor is the 'dishonesty' interpretation, which brings us back to ... intent  :-)

Some articles, etc. on self-plagiarism or academic misconduct at link below

http://libguides.wits.ac.za/content.php?pid=165338&sid=2737854

I think Denise hit the nail on the head in her comment of August 28: "If you use large chunks of previous works of yours, e.g. conference papers, articles, chapters, etc., then you need to reference those just as you would with anyone else's works you use."

Sometimes this can be done with a general footnote at the beginning of a paper, article, or chapter, including words like "This section is a revised and expanded version of the material presented in ...."

Another possible clarification could be: "The definition of this concept was originally published in ...."

Or "The results of this survey were presented in ...; here I shall propose a novel interpretation."

In each case a reference to one's earlier work should be inserted in place of the ellipsis.

Even if the words have changed, it is worthwhile to cite one's previous publications when repeating ideas, just as we do when acknowledging the ideas of other authors.

Concha - I am actually less concerned about it than I was.  Along with my original feeling, most posts indicate that a central issue of copyright breech, plagiarism (self or other), academic offence etc. comes down to intent to gain by either misappropriating the work of others, or to gain from work that is protected by copyright and would otherwise have provided 'benefit' to the original author / Cr holder. I think only a superficial view would treat plagiarism as a black and white area.

Any verbatim repetition I make is of minimal length (see Ian's post) & has no motive other than common sense / practicality.  Longer phrases have some 'wriggle-room' to paraphrase.  I now have a book to write on the topic, so it gives the possibility to expand on issues considerably.  This leads to changes in the wording and context, so I am happy that I won't 'offend myself'  ;-)