How to Detect Plagiarism

Two Parts:Detecting Plagiarism Using Online ToolsHoning Your Eyes and Ears to Sniff Out Plagiarism

Plagiarism is knowingly copying literal phrases or whole sentences of someone else's work and passing it off as your own without attribution. With the proliferation of web content, plagiarism has become as easy as "copy and paste," making it something to constantly guard against. Whether you're a teacher, webmaster, or publisher, this article will teach you how to check for plagiarism using online tools as well as honing your very own plagiarism detector.

Part 1
Detecting Plagiarism Using Online Tools

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    Use free online applications that don't require subscriptions or sign-ups to check electronic documents. Google "plagiarism checker" to come up with a host of free web apps that contain boxes where you paste the suspected text. Hit the verify button and let the app scan the internet for instances of duplicate text.
    • If you want to convert PDFs to text, you may do so. Someone turning in a PDF document, while not inherently suspicious, may be a sign that they're trying to avoid being caught. (PDFs often scan as picture documents instead of as text docs.)
    • Good plagiarism checkers will give you a "compare text" function. This function may differ in details across various apps, but the idea is the same: After clicking the verify button, the app will show you highlighted portions of text that are duplicate. This allows you to see what portions of text were copied instead of simply telling you "this article/text/content was copied."
    • Free plagiarism checkers include:
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    Try the poor man's plagiarism scanner — Google. Look for statistically improbable phrases (SIPs) and then plug and chug them into Google to search its massive database for similarities.[1]
    • First, try selecting SIPs (statistically improbable phrases) and bracketing them in quotation marks in the search bar. Quotation marks simply command Google to search for exact replicas of text. If that doesn't turn up anything, take off the quotation marks and hit the search button again to look for plagiaristic similarities.
    • Note that Google does have its limitations. If you're looking for plagiarism on private message boards and social networking sites, Google is less likely to spot instances of plagiarism as it often won't index those sites.
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    Sign up for a subscription service if you intend on searching for plagiarism consistently and en masse. Subscription service like Plagramme and Turnitin are becoming increasingly popular for teachers who want to head off plagiarism by letting their students know that each and every paper they write is going to be analyzed for duplicate content. Of course, you'll probably have to pay for a service like this, but it's money well spent if it gives the teacher peace of mind, allows her to focus on teaching, and sends the students a message about educational integrity.
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    Check the timestamps of all instances of duplicate text to determine which text is original and which is plagiarized. Knowing that two texts have are duplicate often isn't enough; you'll want to know who plagiarized whom. Although it's rare, it could be that the content you thought was plagiarized has been plagiarized from. There's a big difference, of course. Weeding out who plagiarized from whom will save you the embarrassment of accusing someone of plagiarism who, in fact, did nothing wrong.

Part 2
Honing Your Eyes and Ears to Sniff Out Plagiarism

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    Look for sudden changes in diction or overly complex language. The plagiarist will often lift phrases or whole sentences from others' work because they think it sounds or looks especially good — e.g. fancy. Often, what the plagiarist thinks sounds good is overly technical or academic language. If words like "recondite" "sibilant" or "antepenultimate" suddenly start cropping up out of nowhere, check the text for plagiarism.
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    Look for text that doesn't fit the assignment or content that doesn't fit the scope of the article. If you're a teacher and the student turns in a paper that's not quite on topic or maddeningly tangential, it's a sign that the words could have been plagiarized: Because most original content has "spins" — opinions or angles that distinguish it from the rest of the herd — it's very hard to lift large portions of content directly from other sources and still make it apply to your given topic or angle.
    • If you're a teacher, give out very specific, unusual, or adventurous prompts to your students. This has two advantages. It makes plagiarism much harder because there's less content to pilfer from, and it encourages your students to think about ideas they're not usually exposed to.
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    Keep an eye out for unnatural shifts in tone. Much like changes in diction, shifts in tone can be a red flag. If one sentence reads "I do not think the death penalty is a good thing" and the next sentence reads "Disproportionate numbers of black men are subjugated under the so-called 'legal' yoke of deterrence in what baldly amounts to racism," the shift in tone probably merits investigation.
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    Look for multiple fonts, hyperlinks in physical papers, and other formatting errors. If a student is asked to turn in a paper, and there are multiple fonts, hyperlinks, quotes within quotes, or other formatting errors, it could be a sign of plagiarism. Though none of these in and of themselves clearly spell plagiarism (they could simply be oversights or honest mistakes), they are often cues that some text has been lifted without attribution.
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    Be on the lookout for outdated information. Writing is a snapshot locked in time. That snapshot stays the same even as time moves on. If someone's writing mistakenly names the current president as "George W. Bush," that's generally cause to be suspicious. It seems like an egregious oversight, but it happens more often than you might think.
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    Trust your gut. Often, what will tip off a plagiarist is an intangible feeling you have about their writing. Something just doesn't fit. There may be nothing that you can lay your finger on, but if it appears "off," trust your judgment. It never hurts to check.


  • Google Docs is very good at migrating documents to the web
  • Google Docs provides a readability scale. Evaluate readability of scores of students' now against their first written assignment.


  • You may be able to slip some stolen material past supervisors and etc. but eventually you will be caught.

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Categories: Publishing