Last update 25 February, 2013; R. Hill
Instructors who assign writing projects occasionally find themselves uncomfortably suspicious of the originality of student work, and, having heard that the Internet is a rich source of plagiarized material, wonder how to search for a possible source of that work. Many Internet sites do indeed provide self-published commentary and fiction, many provide documents as a public service by government agencies, and some have been set up to sell papers and essays outright (http://www.snrinfo.com/duenow/).
The staff of the Ellbogen Center for Teaching and Learning does not, in general, recommend the use of software to detect plagiarism, but rather recommends that students be given developmental assignments, turning in progress reports, prospectuses, drafts, and bibliographies, both to discourage plagiarism and to encourage good research and revision. The Council of Writing Program Administrators explains this issue in a position statement (http://wpacouncil.org/positions/WPAplagiarism.pdf) that makes sense to us, and our own LeaRN program gives some suggestions in this document: Creating Assignments that Discourage Plagiarism.
We are investigating purpose-built software to assess both its benefits in general and the features of specific products. For the time being, we recommend
For straight plagiarism detection, please note that, in our tests, in which we formulated papers that copied material from Internet sources, a simple Google search performed as well as anything else, even on variations of the text.
Any mechanical text search is a simple tool only and should play a minor part in assessment. We maintain that both positive matches and negative results should lead to the same step-- a conversation with the student about both the subject matter and the writing process-- and that this conversation is the only reliable indicator of what's going on, anyway.
Some other resources that might help: