Why Did the Incumbency Advantage in U.S. House Elections Grow?

Theory: A simple rational entry argument suggests that the value of incumbency not just of a direct effect, reflecting the value of resources (such as staff) to legislative office, but also of an indirect effect, reflecting the fact that challengers are less likely to contest incumbent-held seats. The indirect is the product of a scare-off effect-the ability of incumbents to scare off -quality challengers-and a quality effect-reflecting how much electoral advantage party accrues when it has an experienced rather than an inexperienced.: The growth of the overall incumbency advantage was driven principally increases in the quality effect.: We use a simple two-equation model, estimated by ordinary least-squares, to analyze U. S. House election data from 1948 to 1990.: Most of the increase in the incumbency advantage, at least down to 1980, through increases in the quality effect (i. e. , the advantage to the incumbent of having a low-quality challenger). This suggests that the task for those to explain the growth in the vote-denominated incumbency advantage is explain why the quality effect grew. It also suggests that resource-based explanations the growth in the incumbency advantage cannot provide a full explanation.