Politicians differ in their ability to implement some policy. In an election, candidates make commitments regarding the plans they will try to implement if elected. These serve as a signal of true ability. In equilibrium, candidates make overambitious promises. The candidate with the highest...

This article analyzes under which conditions a manager can motivate a junior worker by verbal communication, and explains why communication is often tied up with organizational choices as job enlargement and collaboration. Our model has two important features. First, the manager has more...

The paper considers the pricing decision by a seller who has private information about quality. It is shown that, contrary to widespread belief, high quality products may be sold with positive probability even when buyers have no private information. The separating equilibria have a very simple...

This paper surveys the literature on group selection. I describe the early contributions and the group selection controversy. I also describe the main approaches to group selection in the recent literature; fixation, assortative group formation, and reproductive externalities.