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



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

Time Between Tests



The Candy Auction


What to do?

How to Cheat in Online Courses




Question of the Day: How to Stop Restroom Sabotage?


Hello Dubner & Levitt,



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.

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.

The Debate over Teacher Merit Pay: A Freakonomics Quorum





Forgive Student Loans? Worst Idea Ever.

There's an argument going around right now that forgiving the country's student loan debt would have a stimulative effect on the economy. This online petition by, an offshoot of, has nearly 300,000 signatures. Its basic argument is this:
