|PlanScore.org—a new website developed by redistricting experts and Silicon Valley coding experts— allows citizens to upload proposed state districting maps and instantaneously have them scored for partisan symmetry using three widely-accepted measures: the efficiency gap, partisan bias, and the mean-median difference. This scoring is based on precinct-level data and resembles how mapmakers evaluate their own plans. Until now, this information was available primarily to experts with access to costly software.
“We are thrilled to be able to bring PlanScore to the public,” said PlanScore’s executive director Michal Migurski, a geospatial code and data expert who recently served as chief technology officer of Code for America. “With crucial information at their fingertips, citizens will be more empowered to hold their elected officials accountable for producing maps that strengthen rather than detract from our democracy.”
In addition to allowing citizens to score maps, the website offers historical data for state house and U.S. congressional district plans from 1972 to the present. Presently, the website enables citizens to score proposed maps for Pennsylvania, with Wisconsin, North Carolina, Maryland and Ohio coming soon. By 2020, PlanScore plans to allow maps to be scored for all 50 states.
An analysis conducted through PlanScore shows that the Pennsylvania congressional map proposed February 9 by Republican legislative leaders to meet the state Supreme Court’s order is still seriously skewed in favor of Republican candidates and voters. The new map was scored for partisan symmetry using the three measures mentioned above. The proposed congressional map has an efficiency gap of 10.9 percent, a partisan bias of 11.5 percent, and a mean-median difference of 5.8 percent, all in the direction of the Republicans who control the legislature. For each of these measures, scores of zero reflect a mapping scheme with no skew. This compares to the present congressional map with an efficiency gap of 14.3 percent, a partisan bias of 15.9 percent, and a mean-median difference of 5.5 percent, all in a Republican direction.
“This new proposal by the legislative leadership in Pennsylvania reveals the same large and durable Republican advantage as the plan the state Supreme Court struck down,” said PlanScore board member and University of Chicago Law School Professor Nicholas Stephanopoulos. “PlanScore instantaneously discloses this information, which previously was only available to politicians and their hired experts. PlanScore will be an invaluable tool whenever district lines are being drawn, making their partisan implications clear for all to see.”
PlanScore is a non-partisan website and tool developed by redistricting and coding experts. Its board members include: Dr. Eric McGhee, inventor of the efficiency gap; Dr. Simon Jackman, CEO of the US Studies Centre at the University of Sydney and formerly Professor of Political Science and Statistics at Stanford University, and an expert witness on the measures of partisan symmetry in the Gill v. Whitford Wisconsin gerrymandering case; Nicholas Stephanopoulos, Professor of Law at the University of Chicago Law School and co-counsel in Gill v. Whitford; Ruth Greenwood, Senior Legal Counsel at the Campaign Legal Center and co-counsel in Gill v. Whitford; and Michal Migurski, geospatial coding and data expert who recently served as chief technology officer of Code for America.