Is plagiarism detection software helping students plagiarize?

I've not had much experience using plagiarism-detecting software.   The types of assignments we have our students do results in too many false-positives (there's only so many ways of saying "Take on an empty stomach").


David E. Herrington has an essay on his blog where he reflects on the ethics of plagiarism-detecting software.  He makes an interesting observation:

...Turnitin offers another product called WriteCheck that allows students to “check [their] work against the same database as Turnitin.”  .... WriteCheck warned me that “a significant amount of this paper is unoriginal” and advised me to revise it.  After a few hours of right-clicking and scrambling, I resubmitted it and WriteCheck said it was okay, being cleansed of easily recognizable plagiarism.

Turnitin is playing both sides of the fence, helping instructors identify plagiarists while helping plagiarists avoid detection.  It is akin to selling security systems to stores while allowing shoplifters to test whether putting tagged goods into bags lined with aluminum thwart the detectors.

It takes a little while to get to that part of the essay, but it's an interesting read overall.