Of course, the benefit of using services, such as Turnitin, is that you can have the student submit the work and the service automatically provides you with a report of all of the material that it has identified as being problematic. For those instructors that teach large classes and have a lot of papers to check, these types of services can save a lot of time and effort and are, in my opinion, well worth the investment.
As for false positives, I am not exactly sure how these are being defined in this discussion, but one issue that I believe is happening increasingly is that certain sentences that are flagged down as having been copied from other sources tend to be nothing more than common expressions used by inexperienced writers or some other sort of match that strongly suggest pure coincidence. Thus, for example, when I see a Turnitin report that lists several instances of 'plagiarism', say 20% that amount to separate 1% or 2% snippets each from a different source, particularly if these are identified as being from different students from various other universities for a total of 10-12 different web pages, my sense is that these are likely coincidental matches (i.e., false positives?). As Ken points out, plagiarism is often done by lazy students whose MO tends to be the misappropriation of larger chunks of text from a couple of sources. After all, getting smaller amounts of material from many different sources is much more work than most lazy students are willing to do! ;-) Ken, I wonder if you would deem it appropriate -and/or if it is not too much trouble- to share with us how it was that these students were able to fool the service that your institution was testing. Miguel Paul Bernhardt wrote: > > > I want to thank folks for their responses to my question. > > I was suspecting false negatives might be a problem, too. > > If y'all have more to share on plagiarism software in general, I'm happy > to hear more. I may want to build some ammunition to take to our IT people. > > Thanks! > > Paul > I am not a fan of any of the well-known commercial anti-plagiarism packages because I can generate both false positives and false negatives easily. One semester, I offered extra-credit in a couple of classes to students who could sneak plagiarised material past a commercial package and show me how they did it. More than 80% of the students in the classes could do so and several students showed me more than 1 way. (We were testing the product for adoption. I am amazed that schools are buying these services without testing. Instead, schools seem to rely on sales pitches and testimonials.) Finally, many cases of plagiarism are done by very lazy students. Doing Google searches on suspicious phrases often produces the copied document on the first page of searches. Ken --------------------------------------------------------------- Kenneth M. Steele, Ph.D. [email protected] Professor and Assistant Chairperson Department of Psychology http://www.psych.appstate.edu Appalachian State University Boone, NC 28608 USA --------------------------------------------------------------- --- You are currently subscribed to tips as: [email protected]. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13482.917fac06d4daae681dabfe964ca8c74e&n=T&l=tips&o=1483 or send a blank email to leave-1483-13482.917fac06d4daae681dabfe964ca8c...@fsulist.frostburg.edu --- You are currently subscribed to tips as: [email protected]. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5&n=T&l=tips&o=1487 or send a blank email to leave-1487-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
