THE INCUMBENCY ADVANTAGE IN MULTIMEMBER DISTRICTS - EVIDENCE FROM THEUS STATES

Studies of the incumbency advantage in U.S. state legislative election s have usually been limited to the relatively few states that use sing le-member districts exclusively. In this paper we provide a method for computing the incumbency advantage in multimember districts, based on the Gelman-King (1990) estimator for single-member districts, and use it to estimate the incumbency advantage in 40 U.S. states over the pe riod 1970-86. We find that the incumbency advantage has increased in s tates using multimember districts but at a substantially lower average rate than in states with single-member districts. We also find that s tates in which legislators have more opportunity or ability to perform casework services for their constituents are also those in which the incumbency advantage is larger.