Plagiarism Checkers: Dispelling 5 Misunderstandings

The growth of the Internet over the past decade has given us unprecedented access to information. Unfortunately, one of the side effects of this new-found access has been an increase in plagiarism.

With vast content available on the web, it has never been easier to copy and paste proprietary content from the web and pass it off as ones own writing. In response to this practice, plagiarism checkers tout the ability to locate plagiarism in written work.  However, several misunderstandings have arisen about how these services work and should be used.

Like all tools, plagiarism checking software needs to be used properly in order to be effective. To get the maximum benefit, it is important to understand a few misunderstandings surrounding plagiarism checkers. 


Misunderstanding 1: Plagiarism Checkers Automatically Identify Plagiarism

Plagiarism checker software works by comparing submitted text against a database, and identifying identical, or near-identical passages. Many believe that what a plagiarism detector flags as a match is automatically plagiarized material.

It is important to understand that a highlighted passage only represents a possible act of plagiarism and that only a human can make the final judgment as to whether or not a passage is plagiarized.  For example, a quote might be flagged as an exact match, but has quotation marks and a citation; a careful reviewer could determine that this match is not plagiarism.

Furthermore, plagiarism reports often provide a percent match, that is, what percentage of the paper comes from other sources.  What matters is not the amount of matching material detected, but whether or not the duplicate content is used ethically, with proper attribution.

Misunderstanding 2: Plagiarism Checkers Are Used by Plagiarists

It is easy to mistake a plagiarism checker tool as being nothing more than a “plagiarism cop” that is designed to detect and stop plagiarists. While such tools can locate blatant forms of plagiarism, they are beneficial to check for weak writing practices, such as poor paraphrasing, missing citations, and even improper grammar.  In fact, researchers are increasingly running their work through plagiarism checker software before submitting it for publication in an attempt to catch any mistakes or errors that they might have made in the writing process.

According to an internal customer survey conducted by plagiarism detectors WriteCheck and iThenticate, the majority of customers report using the services not to check for problematic issues, rather for peace of mind, to ensure quality work.

In academia, journals are using plagiarism software to detect duplicative publication, sometimes referred to as self-plagiarism.  Self-plagiarism might occur when a researcher submits an article to a journal before learning that it was accepted elsewhere or when an author relies too heavily on their self-authored passages from previously published works.

While plagiarism checker tools can detect the work of unethical writers, often they are used to detect unintentional plagiarism and common writing mistakes. 

Misunderstanding 3: Plagiarism Checkers Are Not Accurate

Many assume that, since plagiarism checker services miss all matched content and can produce false positives, they are inaccurate.  However, when it comes to the intended use of plagiarism checking tools, that is, identifying potential plagiarism in written work, the tools available are accurate.

According to John Barrie, the co-founder of Turnitin, to successfully rewrite a paper so that it passes through their plagiarism checking tools, one has to alter or replace every third word. This means that plagiarism checker tools can detect very short passages of content—including paraphrased passages—making the software difficult to fool, even with rewriting.

Regarding false positives, or text that is flagged by a plagiarism detector but is not plagiarized, it is important to remember the first myth and note that plagiarism checkers only detect matching text; it requires human review to determine whether or not there is evidence of plagiarism.  Even still, plagiarism checkers produce few false positives and are accurate at highlighting problematic text matches that require careful evaluation.

Additionally, plagiarism reports can easily and effectively help publishers review publications for plagiarism. Editor-in-chief of the New York Quarterly Magazine, Raymond Hammond, said:

“I have found iThenticate reports to be very thorough, easy to understand and accurate.”

Misunderstanding 4: Plagiarism Detectors Are Easy to Deceive

For as long as there have been plagiarism detection tools, there have been those trying to ”cheat” the system, such as using macros, altering characters, or employing other “tricks” to bypass these automated systems.  However, these tricks are outdated and ineffective.

Tabitha Edwards, Senior Product Manager with Turnitin, reports:

“The Turnitin service is continually improved to circumvent cheat methods that we find online and methods that we identify on our own.”

Some suggest that they can fool plagiarism checkers by “wordsmithing” or significantly altering a passage to avoid matching text.  However, as evidenced above in myth three, rewriting a paper would require editing at least every third word, which, in short, is more difficult than accurately paraphrasing and documenting a source.

Misunderstanding 5: All Plagiarism Checker Tools Are The Same

While free plagiarism checkers exist, they are generally not ideal for professional use. Not only do they typically have much smaller databases, but they may also be less accurate and may not return quality reports.

For scholarly and professional work in particular, it is crucial that plagiarism checkers have the most extensive database possible.  Many free checkers are limited to Internet content only, while paid subscriptions offer access to journal articles, books, conference proceedings, research manuscripts, etc.  These proprietary content databases require partnerships and special agreements.

When choosing a plagiarism checker, organizations and individual writers should choose the right tool for their specific needs. Turnitin, for example, serves educational institutions and contains a database of academic essays. iThenticate is best suited for research and publishing organizations with its extensive library of scholarly and other published content.

In the end, professional plagiarism checkers are worth the cost; their access to proprietary content in addition to Internet material increases the accuracy of their reports.


Contrary to what many have come to believe, plagiarism checker tools are not all-knowing applications designed to catch academic cheaters and plagiarists. They are tools designed to help detect duplicative content and aid in identifying potential plagiarism.

While they cannot serve as a substitute for human judgment, they are not trivial. They are also not burdens on the writing and editing process, but rather, tools that can help streamline those processes if used correctly.

Though a great deal of myths have evolved around plagiarism detectors, the truth is they are tools to help catch mistakes, avoid issues with duplicate content and preserve the reputations of students, researchers and publishers alike.



 Plagiarism Detection Software Misconceptions