Seats, Votes, and Gerrymandering: Estimating Representation and Bias in State Legislative Redistricting

The Davis V. Bandemer case focused much attention on the problem of using statistical evidence to demonstrate the existence of political gerrymandering. In this paper, we evaluate the uses and limitations of measures of the seat-votes relationship in the Bandemer case. We outline a statistical method we have developed that can be used to estimate bias and the form of representation in legislative redistricting. We apply this method to Indiana state House and Senate elections for the period 1972 to 1984 and demonstrate a maximum bias of 6.2% toward the Republicans in the House and a 2.8% bias in the Senate.