A student in my research writing skills class asked a great question last week about plagiarism. It is clear that copying another writer’s sentence and presenting it as your own work (i.e. without quotation marks), even if you include the correct citation, is not acceptable and would be considered plagiarism by most academics in the U.S. (see my video for more on this).
However, what do you about mathematical equations? You can’t paraphrase an equation, right? (Genuine question: the last math class I took was … many years ago!) And you don’t use quotation marks with an equation. So, what can you do? The situation would be that in your paper, you want to use an equation that was derived (or, invented?) by another scholar. Can you:
(1) Just use the equation and assume that the reader knows who created it?
(2) Paraphrase the equation by rewriting it in a different form, and including the correct citation?
(3) Use the equation exactly as it appeared in the original and include the correct citation?
This useful guide from Penn State University seems to imply that it is sufficient to cite the equation or statistic, so option 3 seems a good choice (this guide from the University of Florida and this excellent example from McMaster University in Canada agree). Everything I’ve read on this topics supports the basic principle: make the distinction between what you said and what other people said absolutely clear!
However, I suspect there may be differences between disciplines (math, stats, biostatistics, etc.), so you should definitely check with an advisor or journal editor.
I’d welcome your experience and suggestions on this question.