Entries Tagged "schools"

Page 3 of 8

The Effectiveness of Plagiarism Detection Software

As you’d expect, it’s not very good:

But this measure [Turnitin] captures only the most flagrant form of plagiarism, where passages are copied from one document and pasted unchanged into another. Just as shoplifters slip the goods they steal under coats or into pocketbooks, most plagiarists tinker with the passages they copy before claiming them as their own. In other words, they cloak their thefts by scrambling the passages and right-clicking on words to find synonyms. This isn’t writing; it is copying, cloaking and pasting; and it’s plagiarism.

Kerry Segrave is a right-clicker, changing “cellar of store” to “basement of shop.” Similarly, he changes goods to items, articles to goods, accomplice to confederate, neighborhood to area, and women to females. He is also a scrambler, changing “accidentally fallen” to “fallen accidentally;” “only with” to “with only;” and, “Leon and Klein,” to “Klein and Leon.” And, he scrambles phrases within sentences; in other words, the phases of his sentences are sometimes scrambled.

[…]

Turnitin offers another product called WriteCheck that allows students to “check [their] work against the same database as Turnitin.” I signed up and submitted the early pages of Shoplifting. WriteCheck matched many of Shoplifting’s phrases to those of the i>New York Times articles in its library of student papers. Remember, I submitted them as a student paper to help Turnitin find them; now WriteCheck has them too! 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.

Posted on September 19, 2011 at 6:35 AMView Comments

Degree Plans of the Future

You can now get a Master of Science in Strategic Studies in Weapons of Mass Destruction. Well, maybe you can’t:

“It’s not going to be open enrollment (or) traditional students,” Giever said. “You worry about whether you might be teaching the wrong person this stuff.”

At first, the FBI will select students from within its ranks, though Giever wants to open it to other law enforcement agencies. Rather than traditional tuition, agencies will contract with the school, paying about $300,000 a year for groups of 15 to 20 full-time students, according to documents submitted to the board of governors of the State System of Higher Education.

Posted on July 15, 2011 at 6:31 AMView Comments

Man-in-the-Middle Attack Against the MCAT Exam

In Applied Cryptography, I wrote about the “Chess Grandmaster Problem,” a man-in-the-middle attack. Basically, Alice plays chess remotely with two grandmasters. She plays Grandmaster 1 as white and Grandmaster 2 as black. After the standard opening of 1. e4, she just replays the moves from one game to the other, and convinces both of them that she’s a grandmaster in the process.

Detecting these sorts of man-in-the-middle attacks is difficult, and involves things like synchronous clocks, complex cryptographic protocols, or — more practically — proctors. Proctors, of course, can be fooled. Here’s a real-world attempt of this type of attack on the MCAT medical-school admissions test.

Police allege he used a pinhole camera and wireless technology to transmit images of the questions on a computer screen back to his co-conspirator, Ruben, at the University of British Columbia.

Investigators believe Ruben then tricked three other students, who thought they were taking a multiple choice test for a job to be an MCAT tutor, into answering the questions.

The answers were then transmitted back by phone to Rezazadeh-Azar, as he continued on with the test in Victoria, police allege.

And as long as we’re on the topic, we can think about all the ways to hack this system of remote exam proctoring via webcam.

Posted on June 2, 2011 at 7:32 AMView Comments

Changing Incentives Creates Security Risks

One of the things I am writing about in my new book is how security equilibriums change. They often change because of technology, but they sometimes change because of incentives.

An interesting example of this is the recent scandal in the Washington, DC, public school system over teachers changing their students’ test answers.

In the U.S., under the No Child Left Behind Act, students have to pass certain tests; otherwise, schools are penalized. In the District of Columbia, things went further. Michelle Rhee, chancellor of the public school system from 2007 to 2010, offered teachers $8,000 bonuses — and threatened them with termination — for improving test scores. Scores did increase significantly during the period, and the schools were held up as examples of how incentives affect teaching behavior.

It turns out that a lot of those score increases were faked. In addition to teaching students, teachers cheated on their students’ tests by changing wrong answers to correct ones. That’s how the cheating was discovered; researchers looked at the actual test papers and found more erasures than usual, and many more erasures from wrong answers to correct ones than could be explained by anything other than deliberate manipulation.

Teachers were always able to manipulate their students’ test answers, but before, there wasn’t much incentive to do so. With Rhee’s changes, there was a much greater incentive to cheat.

The point is that whatever security measures were in place to prevent teacher cheating before the financial incentives and threats of firing wasn’t sufficient to prevent teacher cheating afterwards. Because Rhee significantly increased the costs of cooperation (by threatening to fire teachers of poorly performing students) and increased the benefits of defection ($8,000), she created a security risk. And she should have increased security measures to restore balance to those incentives.

This is not isolated to DC. It has happened elsewhere as well.

Posted on April 14, 2011 at 6:36 AMView Comments

Term Paper Writing for Hire

This recent essay (commentary here) reminded me of this older essay, both by people who write student term papers for hire.

There are several services that do automatic plagiarism detection — basically, comparing phrases from the paper with general writings on the Internet and even caches of previously written papers — but detecting this kind of custom plagiarism work is much harder.

I can think of three ways to deal with this:

  1. Require all writing to be done in person, and proctored. Obviously this won’t work for larger pieces of writing like theses.
  2. Semantic analysis in an attempt to fingerprint writing styles. It’s by no means perfect, but it is possible to detect if a piece of writing looks nothing like a student’s normal writing style.
  3. In-person quizzes on the writing. If a professor sits down with the student and asks detailed questions about the writing, he can pretty quickly determine if the student understand what he claims to have written.

The real issue is proof. Most colleges and universities are unwilling to pursue this without solid proof — the lawsuit risk is just too great — and in these cases the only real proof is self-incrimination.

Fundamentally, this is a problem of misplaced economic incentives. As long as the academic credential is worth more to a student than the knowledge gained in getting that credential, there will be an incentive to cheat.

Related note: anyone remember my personal experience with plagiarism from 2005?

Posted on November 16, 2010 at 6:36 AMView Comments

High School Teacher Assigns Movie-Plot Threat Contest Problem

In Australia:

A high school teacher who assigned her class to plan a terrorist attack that would kill as many innocent people as possible had no intent to promote terrorism, the school principal said yesterday.

The Year-10 students at Kalgoorlie-Boulder Community High School were asked to pretend they were terrorists making a political statement by releasing a chemical or biological agent on “an unsuspecting Australian community”.

The task included choosing the best time to attack and explaining their choice of victims and what effects the attack would have on a human body.

“Your goal is to kill the MOST innocent civilians,” the assignment read.

Principal Terry Martino said he withdrew the assignment for the class on contemporary conflict and terrorism as soon as he heard of it. He said the teacher was “relatively inexperienced” and it was a “well-intentioned but misguided attempt to engage the students”.

Sounds like me:

It is in this spirit I announce the (possibly First) Movie-Plot Threat Contest. Entrants are invited to submit the most unlikely, yet still plausible, terrorist attack scenarios they can come up with.

Your goal: cause terror. Make the American people notice. Inflict lasting damage on the U.S. economy. Change the political landscape, or the culture. The more grandiose the goal, the better.

Assume an attacker profile on the order of 9/11: 20 to 30 unskilled people, and about $500,000 with which to buy skills, equipment, etc.

For the record, 1) I have no interest in promoting terrorism — I’m not even sure how I could promote terrorism without actually engaging in terrorism, 2) I’m pretty experienced, and 3) my movie-plot threat contests are not misguided. You can’t understand security defense without also understanding attack.

Australian police are claiming the assignment was illegal, so Australians who enter my movie-plot threat contests should think twice. Also anyone writing a thriller novel about terrorism, perhaps.

An AFP spokeswoman said it was an offence to collect or make documents preparing for or assisting a terrorist attack.

It was also illegal to be “reckless as to whether these documents may assist or prepare for a terrorist attack”.

Posted on August 31, 2010 at 6:42 AMView Comments

Detecting Cheating at Colleges

The measures used to prevent cheating during tests remind me of casino security measures:

No gum is allowed during an exam: chewing could disguise a student’s speaking into a hands-free cellphone to an accomplice outside.

The 228 computers that students use are recessed into desk tops so that anyone trying to photograph the screen—using, say, a pen with a hidden camera, in order to help a friend who will take the test later—is easy to spot.

Scratch paper is allowed—but it is stamped with the date and must be turned in later.

When a proctor sees something suspicious, he records the student’s real-time work at the computer and directs an overhead camera to zoom in, and both sets of images are burned onto a CD for evidence.

Lots of information on detecting cheating in homework and written papers.

Posted on July 9, 2010 at 6:34 AMView Comments

Sidebar photo of Bruce Schneier by Joe MacInnis.