Michigan State-Michigan collaboration to measure Partisan Advantage in redistricting

October 27, 2022

The effect of redistricting will be a major topic as the results of the 2022 elections are analyzed in the weeks and months ahead. In some states, districts were drawn by partisan legislatures; in others those maps were challenged in the courts with varying results; and in Michigan for the first time, state and federal districts were established by the Michigan Independent Citizens Redistricting Commission (MICRC).

How fairly will those new districts reflect the will of the voters? Will there be a disconnect between the number of votes and the elected representatives?

A Michigan State University-University of Michigan collaboration has studied the issue and created a user-friendly tool that will help the public assess election fairness and track election outcomes. The Partisan Advantage Tracker “measures the number of seats each party should win given the number of votes that they received and the number of seats each party would win, with these same votes, according to the current district maps. The difference between the number of seats each party would win and the number of seats it should win, is the partisan advantage of the current map, given these votes.”

LSA student Henry Fleischmann (BS ‘23) worked with the Ford School’s Center for Local, State, and Urban Policy (CLOSUP) in its ongoing collaboration with MSU’s Institute for Public Policy and Social Research (IPPSR). 

“One of the most frustrating aspects of gerrymandering is that it is often impossible to visually detect partisan manipulation of the maps. However, in recent years researchers across a spectrum of fields—with backgrounds in law, political science, economics, pure mathematics, and computer science all represented—have proposed numerous techniques to detect malicious gerrymanders. These tools can form the basis of legal arguments that districting proposals violate state districting fairness criteria. I believe that it is now possible to end the practice of partisan gerrymandering,” he says.

He also produced a CLOSUP student working paper, Evaluating the Outcome of the 2022 United States Redistricting Cycle: A Nonpartisan Review.

MSU Professor of Economics and Political Science Jon X. Eguia had been working on the issue for years. Eguia says, “We were trying to answer a simple question: ‘Are electoral maps fair?’” 

Previous tools to assess fairness and calculate political gains and losses from newly drawn maps were incomplete, he notes. 

And while developing the new Partisan Advantage Tracker, Eguia also authored a detailed analysis of the new maps created by the MICRC, evaluating their performance across multiple criteria that are required as part of Michigan’s new approach to redistricting. 

Fleischmann explains that the primary purpose of the tracker is to make evidence of gerrymandering easily accessible to the public. The tracker displays the average partisan outcomes on the new 2022 maps and measures those outcomes to well-established fair benchmarks, as opposed to simply comparing them to previously-drawn maps.

Eguia says this tool can be updated every two years, and could ultimately affect the next redrawing of districts across the country. He credits Fleischmann’s desire to apply his mathematics and computer science ability to the public good.

“He wants to make the world a better place through doing things better and creating  tools the public can use. He is a well-informed individual whose vocation is to serve the public. That’s the kind of public servant we want,” he says.

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