In class last week, I did an activity with the students that demonstrated free-riding. Students are given a hypothetical dollar and have the option of keeping their dollar or contributing to the Public Account. For each dollar in the Public Account, everyone in the class receives some amount (I use $0.10 in the big class). So, for example, if 100 students contribute to the Public Account, everyone gets $10: anyone who contributed would have $10 but those who kept their dollar would have $11. We do several rounds, with some discussion at various points, and to give students incentive to think about maximizing their 'profit', I give them bonus points equal to some percentage of their total earnings.
As expected, some students free-ride; in my class, there were about 75% who contributed to the Public Account in the first round but that quickly dropped to 50% in the second round, about 30% in the third round and about 15% in the fourth round. At that point, we had some discussion where I pointed out that if everyone contributed to the Public Account, they would all earn more than anyone had earned in any of the previous rounds. Contributions in the next round were back up to about 60% but then went back down to 30% in the sixth and final round. We talked a little about how the results might have been different if, instead of using their clickers, I had asked them to raise their hands, or otherwise signal their contribution in a way that was more visible to everyone else. Some students also commented that they were willing to contribute when the majority of the rest of the class did but when they saw that so many others were free-rising, they felt they might as well also.
All of this is pretty much what I expected; I've tried different versions of this in various classes, almost always with similar results. It's always a memorable activity for students. But the dilemma I always face afterward is this: do I really want to reward free-riding? I know that I need to tell the students I'm going to base their points on their earnings, in order to create realistic incentives and make the point about free-riding that I want them to see firsthand. But if I actually do assign points that way, then students who free-ride in every round end up with the most points and that sort of bugs me. I think about those experiments I've heard about where in lab situations, econ students are more likely than students in other majors to free-ride and I think: is that really what we want?
What I usually end up doing is give all students who participate in every round the number of points that they would have gotten if they had been free-riders, regardless of their actual choices, and hope that no one really notices (most students are just happy to get some bonus points and since they check their scores in Blackboard, I'm not sure they are comparing their bonus points to other students). But if anyone else has a better solution, I'd love to hear it!
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