HOMO ECONOMICUS IS EVEN DEAD IN LAKE WOBEGON:

Early in my teaching career I managed to get most of the students in my class mad at me. A midterm exam caused the problem.

I wanted the exam to sort out the stars, the average Joes and the duds, so it had to be hard and have a wide dispersion of scores. I succeeded in writing such an exam, but when the students got their results they were in an uproar. Their principal complaint was that the average score was only 72 points out of 100.

What was odd about this reaction was that I had already explained that the average numerical score on the exam had absolutely no effect on the distribution of letter grades. We employed a curve in which the average grade was a B+, and only a tiny number of students received grades below a C. I told the class this, but it had no effect on the students' mood. They still hated my exam, and they were none too happy with me either. As a young professor worried about keeping my job, I wasn't sure what to do.

Finally, an idea occurred to me. On the next exam, I raised the points available for a perfect score to 137. This exam turned out to be harder than the first. Students got only 70 percent of the answers right but the average numerical score was 96 points. The students were delighted! [...]

In the eyes of an economist, my students were "misbehaving." By that I mean that their behavior was inconsistent with the idealized model at the heart of much of economics. Rationally, no one should be happier about a score of 96 out of 137 (70 percent) than 72 out of 100, but my students were. And by realizing this, I was able to set the kind of exam I wanted but still keep the students from grumbling.

This illustrates an important problem with traditional economic theory. Economists discount any factors that would not influence the thinking of a rational person. These things are supposedly irrelevant. But unfortunately for the theory, many supposedly irrelevant factors do matter.

Economists create this problem with their insistence on studying mythical creatures often known as Homo economicus.

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