Faulty Communication

The electronic mail game of Rubinstein (1989) showed that a lack of common knowledge generated by faulty communication can make coordinated action impossible. This paper shows how this conclusion is robust to having a more realistic timing structure of messages, more than two players who meet publicly but not as a plenary group, and strategic decisions about whether to communicate. The electronic mail game of Rubinstein (1989) showed that a lack of common knowledge generated by faulty communication can make coordinated action impossible. This paper shows how this conclusion is robust to having a more realistic timing structure of messages, more than two players who meet publicly but not as a plenary group, and strategic decisions about whether to communicate.Electronic mail, common knowledge, coordination

Coordination, Communication and Common Knowledge: A Retrospective on Electronic Mail Game

Common knowledge plays an important role in coordination problems and coordination problems are central to many areas of economic policy. In this paper, I review some common knowledge puzzles culminating in the electronic mail game. These puzzles may seem distant from practical concerns. However, I then argue why insights derived from this literature are useful in interpreting empirical evidence of how people coordinate under uncertainty and in understanding the role of communication in coordinating behaviour.Common knowledge, Coordination, Communication

Political Correctness

An informed advisor wishes to convey her valuable information to an uninformed decision maker with identical preferences. Thus she has a current incentive to truthfully reveal her information. But if the decision maker thinks the advisor might be biased in favor of one decision, and the advisor does not wish to be thought to be biased, the advisor has a reputational incentive to lie. If the advisor is sufficiently concerned about her reputation, no information is conveyed in equilibrium. In a repeated version of this game, the advisor will care (instrumentally) about her reputation simply because she wants her valuable and unbiased advice to have an impact on future decisions.

Best Response Equivalence

Two games are best-response equivalent if they have the same best-response correspondence. We provide a characterization of when two games are best-response equivalent. The characterizations exploit a dual relationship between payoff differences and beliefs. Some "potential game" arguments (cf. Monderer and Shapley, 1996, Games. Econ. Behav. 14, 124-143) rely only on the property that potential games are best-response equivalent to identical interest games. Our results show that a large class of games are best-response equivalent to identical interest games, but are not potential games. Thus we show how some existing potential game arguments can be extended.Best response equivalence; Duality; Farkas' Lemma; Potential games

GP supply and obesity

We investigate the relationship between GP supply and body mass index (BMI) in England. Individual level BMI is regressed against area whole time equivalent GPs per 1,000 population plus individual and area level covariates. Using IV models we find that a 10% increase in GP supply is associated with a mean reduction in BMI of around 1 kg/m2 (around 4% of mean BMI). Our study suggests that better primary care in the form of reduced list sizes per GP can improve the management of obesity.Obesity; GP supply; Primary care