Archives for students



The Opportunity Cost of an Email

There’s a midterm this week in my class of 550 students, and I have been deluged with emailed questions, many procedural, that are covered in the online daily class summary. (For example, is the test being given in class?)  In the old days, when students came to office hours to ask questions, I wouldn’t have gotten most of these queries.  Regrettably, a student’s opportunity cost of emailing is much less than the cost of an office visit.

Why don’t I raise the cost to students by refusing to answer these emails?  If I thought that would deter all such questions and visits, I would refuse. But even if 20 percent of the emails translate into student visits, I’m better off answering the emails, since each takes me at most 1/5 as long as dealing with the question face-to-face in my office.  This is annoying, but I believe I save time this way.



Calling All International-Econ Undergrads

Elena Malik, communications chair of the 12th annual Carroll Round at Georgetown, writes to solicit applications for a worthwhile event:

The Carroll Round is an annual undergraduate international economics conference at Georgetown University that provides a unique forum for research and discussion among the world’s top undergraduates. Each year, we invite applications from students to present and discuss their work with peers, professors, and policy-makers invited to participate. This year we are honored to host guest speakers including Dr. John B. Taylor and Dr. Janet Currie. We are still recruiting applications from students.

This year’s Carroll Round will be held from April 18-21; more info here.



Time Between Tests

A new working paper (abstract; PDF) by Ian Fillmore and Devin G. Pope examines whether “cognitive fatigue” has any impact on exam results. The researchers looked at the number of days students had between AP exams, and found that resting time matters:

In many education and work environments, economic agents must perform several mental tasks in a short period of time. As with physical fatigue, it is likely that cognitive fatigue can occur and affect performance if a series of mental tasks are scheduled close together. In this paper, we identify the impact of time between cognitive tasks on performance in a particular context: the taking of Advanced Placement (AP) exams by high-school students. We exploit the fact that AP exam dates change from year to year, so that students who take two subject exams in one year may have a different number of days between the exams than students who take the same two exams in a different year. We find strong evidence that a shorter amount of time between exams is associated with lower scores, particularly on the second exam. Our estimates suggest that students who take exams with 10 days of separation are 8% more likely to pass both exams than students who take the same two exams with only 1 day of separation.

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The Candy Auction

As I do each year, I auctioned off candy (this year Reese’s peanut butter cups) to my class.  None were bought at a price above $0.50, all 23 were sold at that price. As usual, a nice illustration of downward-sloping demand curves.  I had kept one piece at the start, extolling its taste while eating half of it (and thus presumably causing an increase in demand).  The other half fell off my lectern, and I stepped in it after returning to the front of the room.  The first half piece of candy was really tasty, and I was dying for another one.  

What to do? Read More »



How to Cheat in Online Courses

An article in Chronicle of Higher Education explains how the increase in online courses has made cheating a lot easier. For example, Bob Smith (not his real name) successfully arranged a test-cheating scheme with several friends.  The tests “pulled questions at random from a bank of possibilities” and could be taken anywhere, but had to be taken within a short window of time each week:

Mr. Smith figured out that the actual number of possible questions in the test bank was pretty small. If he and his friends got together to take the test jointly, they could paste the questions they saw into the shared Google Doc, along with the right or wrong answers. The schemers would go through the test quickly, one at a time, logging their work as they went. The first student often did poorly, since he had never seen the material before, though he would search an online version of the textbook on Google Books for relevant keywords to make informed guesses. The next student did significantly better, thanks to the cheat sheet, and subsequent test-takers upped their scores even further. They took turns going first. Students in the course were allowed to take each test twice, with the two results averaged into a final score.

“So the grades are bouncing back and forth, but we’re all guaranteed an A in the end,” Mr. Smith told me. “We’re playing the system, and we’re playing the system pretty well.”

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Question of the Day: How to Stop Restroom Sabotage?

A reader named Olaf Winter writes in with a problem that perhaps you all can help solve?

Hello Dubner & Levitt,

During a Parent Teacher Association meeting in my son’s high school in Essen, Germany, I heard complaints about a growing problem with unbelievably dirty toilets, or to be more precise, with the problem of adolescent girls smirching, soiling, polluting, dripping and littering at the restrooms.

I’m talking about unrolled packs of toilet paper stuffed into the toilet; about smearings on the walls (with pens in the best case). I forgo the more unsavory details. You probably have an idea of what I mean. The school I am talking about is one of the best schools in town. It is a newly built complex with beautiful architecture, lots of space and light. The pupils have an upper-middle-class background. And still, when they are in the restroom at least some of them behave like savages.

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Does Studying Economics Teach You to Lie?

new paper by Raúl López-Pérez and Eli Spiegelman investigates “truth preferences” — i.e., preferences for being honest versus lying. Their goal was to study whether economics students lie more as a result of their education. Or do liars self-select? From the paper:

Does studying economics give people “maximizing” habits of thought, and thus cause them to  behave more in line with its own predictions, or do people already inclined towards such behavior tend to self-select into economics?

A computer test structured with a slight incentive to lie was administered to 258 students at The Autonomous University of Madrid. The screen showed two colors, and participants were paid 14 euros for declaring blue and 15 euros for declaring green to another person, regardless of the actual color shown on screen. So what happened? According to the authors, the business and economics (“B&E”) majors gamed the system. Read More »



When It Pays to Say “I Don’t Know”

In response to our recent podcast called “Why Is ‘I Don’t Know’ So Hard to Say?,” a reader named Timothy McCollough writes in with a most interesting story. He teaches at a private international school in Santo Domingo, Dominican Republic. His courses include two sections of AP microeconomics, sociology, and “regular economics.” Because it’s a private school, he adds, “we have freer reign to set up classroom incentives and engage students as we see fit.” For instance:

In my classroom, students lose 1/4 point for wrong answers on quizzes. But for writing “I don’t know,” they get 1/4 point. (A correct answer is 1 point). The rationale is that if someone is in a medical emergency, and someone asks me what should be done, the answer “I don’t know” is much preferable to a guess. “I don’t know” leads the questioner to ask someone who hopefully is knowledgeable.

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