Chilean teacher develops world’s best anti-plagiarism software

Professor Juan Velásquez explains how Docode detects copied text, deters cheating, and may change the way we analyze the news.


With every jump in information technology comes a new opportunity for plagiarism, or so it seems to many harried teachers. This time, technology pushed back: anti-plagiarism software Docode flags suspicious text with an unprecedented algorithm, diminishing plagiarism to as low as 2 percent in a trial study.

Universidad de Chile professor Juan Velásquez created the software in collaboration with Sebastián Ríos, Gastón L’Huillier, and Gabriel Oberreuter, at Chile’s leading public university. Their latest version of the advanced anti-plagiarism software can flag copied text even when words have been changed or the order of paragraphs altered.

“This is what you call intrinsic plagiarism,” Velásquez told Chilean daily El Mercurio, speaking on the phone from France. “Each person has a writing style, and with this algorithm you can figure out when a paragraph appears that is completely out of style. Upon detecting this intrinsic plagiarism, we are able to say, ‘this paragraph is strange,’ and with that certainty we improve detection.”

This detail granted the Universidad de Chile team a comfortable win at the PAN competition (Uncovering Plagiarism, Authorship and Social Software Misuse), which awards a prize to the best plagiarism-detection method from around the world. Docode became a phenomenon in Europe, where Velásquez and team have been touring almost constantly ever since.

“They want us to tell them how it works and how it occurred to us,” Velásquez said.

It started, according to the professor, while he was working at a private university four years ago. “Of the 40 assignments I gave, 40 were copies. I was going to fail everyone, but they asked me for another chance. That time, 50 percent were copies. I had to give them a third chance.”

Thanks to a 2009 grant from the Science and Technology Development Fund (Fondef), Velásquez began working on Docode. After a year of software trials, the team conducted a nation-wide survey among students and found that 57 percent of students plagiarize.

“When we began to implement Docode in a few places, we lowered copying to less than 2 percent,” Velásquez said.

And Docode’s plans for the future, after the September award ceremony in the Netherlands? Velásquez sees the software playing a role both in the school and in society.

“The idea is for it to be a tool that’s used in all of the Universidad de Chile, and also in other private universities. We sell the plagiarism detection service. But that’s not really the business, the business is textual analysis, which is to say, analyze how much a piece of news has gone viral. For example, with the student conflict, we could say, ‘look, this is what is most important to the students.’”