A Note on Varying Mutation Rates in 2 x 2 Coordination Games

The model of 2 x 2 coordination games in Kandori, Mailath, and Rob (Econometrica 1993) is extended to allow for a mutation rate that is stochastic over time. The expected time the system spends in the risk dominated equilibrium is systematically underestimated by the standard model in Kandori, Mailath, and Rob (Econometrica 1993) when the latter model's (fixed) mutation rate is equal to the expected mutation rate. A small population result corrects a minor omission in Kandori, Mailath, and Rob (Econometrica 1993).