Comment on 'Estimating incumbency advantage and its variation, as an example of a before-after study'

The incumbency advantage is one of the most widely studied phenomena in political science. In fact, it is one of the few quantities of interest in the field where there is relative agreement not only on its directionality, but also on its relative size. Thus I was somewhat dubious that any significant additions remainder to be made to our understanding; however, Gelman and Huang have in fact made two important contributions.