Description:

"Gerrymandering: What Is It, How Can We Measure It, and What Can We Do About It?"

By Jeanne Clelland, Professor of Mathematics, University of Colorado-Boulder

Co-sponsored with the Global Poverty Research Lab and the Statistics for Evidence-Based Policy and Practice (STEPP) Center

Abstract: Gerrymandering refers to the practice of drawing legislative districts so that one political party wins a disproportionate number of seats relative to their share of the electorate. But how can we tell whether or not districts have been drawn fairly? This is a legal question and, increasingly, a mathematical one, but the mathematical tools used to measure gerrymandering are relatively new and are still evolving rapidly. One promising approach involves using computational and statistical tools to compare a specific districting plan to an “ensemble” consisting of a large number of potential districting plans. This approach, referred to as “outlier analysis,” has the advantage of taking into account the inherent political geography of a region in a way that simpler measures cannot, and it has already begun to play a role in major court cases regarding redistricting in North Carolina, Pennsylvania, and elsewhere. In this talk, Clelland will describe how gerrymandering works and some of the mathematical tools that are being developed to detect it, with a focus on outlier analysis. She will also talk about an ongoing effort to collect data and perform this type of analysis for as many states as possible in advance of the next round of congressional redistricting in 2021.