10,000 Maps to Show That We Can Do Better



Michiganders across the state are ready to draw the line to stop the partisan manipulation by politicians and lobbyists when they draw our election maps behind closed doors. That’s why over 425,000 Michiganders signed Voters Not Politicians’ petition to put an Independent Citizens Redistricting Commission on the November 2018 ballot that would put voters - not politicians - in charge of drawing our district boundaries. Allowing politicians and their lobbyists the power to pick their voters is a conflict of interest and gives them an unfair advantage to keep themselves in power. But what is the basis for this argument – how do we know how bad it is – and how do we know that better is possible?


Not normal

A study by the Brennan Center of Justice measured partisan manipulation in district maps and ranked Michigan as one of only 3 states that have maps with consistently extreme levels of partisan bias. Data analyzed from 2012, 2014, and 2016 elections shows that this is true across all three election years and across several measures of partisan bias.


How do we know that Michigan’s election maps are manipulated? Several opponents point to “self-sorting” - not partisan bias - as the scapegoat. They argue that people naturally move into areas with people that have similar viewpoints as they do, but experts are able to show that Michigan’s current set of district maps are exceptionally more biased than could be considered normal or fair. How do they know this? Math.


The math

Experts use many methods to measure district manipulation. Some use mathematical functions to compare the real outcomes of elections to the expected outcomes, based on voter data and election results. Others use a comparison of votes won to district seats won and compares this to historical data. There’s also the efficiency gap, which measures “wasted” votes, or votes unspent on an election victory.


Dr. Dan Magleby, a professor of political science with a PhD. in Political Science and Government from the University of Michigan, specializes in measuring partisan election map manipulation - known as gerrymandering. Magleby used public US Census data with mapping technology called GIS (geographic information systems) to create 10,000 random, hypothetical Michigan voter district maps. He paired this analysis with 2012 election data to measure if any partisan bias exists in Michigan’s current maps.  




District maps, roadmaps

Magleby’s 10,000 hypothetical maps are computer-generated by randomly dividing the population of Michigan into the same amount of roughly equally sized districts that are contiguous (that is, each district is one continuous space) and adhere to federal laws like the Voting Rights Act. This resulted in thousands of hypothetical possibilities of how voters could be drawn into voting districts. A partisan bias was then measured for each hypothetical map.


For the math fans out there, Magleby measured partisan bias using a mean-median score – a common statistical tool that compares the mean-average of a dataset to the median-middle  to show the amount of skew. For more on mean-median scores in redistricting, click here.


So what do these 10,000 hypothetical maps reveal? Given our population size and geography, how much bias should we expect from a set of election maps? The graph below illustrates the bias produced by a random sample of 1,500 of Magleby’s maps by plotting their mean-median partisan scores. The farther the score is from zero, the stronger the bias.




On the left side in green are all of the scores for the 1,500 hypothetical maps. -1.7 represents the average amount of bias produced by the maps. This is an amount you’d expect to see from a process like “self-sorting,” where voters of the same party typically live in similar areas as each other. On the right side, shown on the same scale but extremely far outside the normal range, is Michigan’s current Congressional map, at -6.7. This is what happens when one political party controls the process and can use big data - like voting history, browsing history, and credit card purchase behavior - to draw maps behind closed doors to give them an unfair advantage in the next decade of elections by hand-picking which voters they do and don’t want in their district.


So which map should we use?

Voters Not Politicians is working to establish a fair system where an Independent Citizens Redistricting Commission of regular voters will draw the maps using a process that is transparent, allows public input and expert consultation, and represents the interests of Michigan voters. The maps drawn by the Commission – with help from experts who will make their methods and data publicly available – will also follow a strict set of criteria, eliminating the practice of drawing districts to give one party or politician an unfair advantage. The final maps will also need to be approved by a majority of the Commissioners with at least 2 Democrats, 2 Republicans, and 2 Commissioners who align with neither party. This impartial and transparent process will give Michigan more fair maps that aren’t drawn with partisan bias or influence.


What the maps offer us

In short, this research shows that we should expect far less partisan bias than what we currently have. It shows that Michigan voters are holding cards dealt from a stacked deck - that our current system is grossly unjust. But the maps are also evidence that we don't have to play that way. It’s time we draw the line. It’s time that we, the voters of Michigan, demand a redistricting process that is fair, impartial and transparent. Here’s how you can help:


Save the Date // save the date and vote YES for an Independent Citizens Redistricting Commission in the November 6 2018 election!


Donate // the politicians and special interests who benefit from the current system will spend millions defending and protecting their unfair advantage. We have to fight back, and that will include advertising and putting together hundreds of local events across Michigan to educate voters on their rights. Donate to Voters Not Politicians here.


Volunteer // we are recruiting volunteers to spread the word in 2018 to help us end gerrymandering in Michigan! If you are interested in being a part of this vital part of the process, please click here.


Stay educated // learn more about gerrymandering and how you can defeat it! Stay up to date on campaign updates and news by signing up for our newsletter here.


Connect // follow us on Facebook and Twitter for updates!


Disclaimer: The maps produced for this analysis were strictly used to measure partisan bias and are not intended or created for the purpose of submitting for consideration for Michigan’s next set of election district maps. The maps created for this project serve only as hypothetical possibilities of what maps might look like if they were not created with the express purpose of gaining as much of an advantage as possible for the party in power. They show that the expertise and technology needed to make this a fair system do exist.  

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