26 ALEXANDER v. SOUTH CAROLINA STATE CONFERENCE OF THE NAACP Opinion of the Court Total Voting Age Population Biden Vote Trump Vote Net Biden Votes Biden Vote % Black Voting Age Population Moved from District 1 to District 6 Precinct 1 1,250 Precinct 2 1,250 400 250 150 62% 250 500 600 -100 45% 0 Yes No Dr. Ragusa’s model considers only the total number of Biden votes in its partisanship analysis. J. S. A. 502a. But legislators aiming to make District 1 a relatively safe Republican seat would be foolish to exclude Precinct 2 merely because it has more Democratic votes than Precinct 1. Instead, they would look at the net Democratic votes and would thus remove Precinct 1, not Precinct 2. Although the use of total votes may be a statistically permissible measure of partisan lean, it is undoubtedly preferable for an expert report to rely on net votes when measuring a district’s partisan lean. The Challengers seek to defend Dr. Ragusa’s report by suggesting that he followed the same methodology as Professor Stephen Ansolabehere, whose report we blessed in Cooper, 581 U. S., at 315, but that is wrong. There are important differences between Dr. Ragusa’s methodology and Professor Ansolabehere’s, 9 and in all events, Professor Ansolabehere’s report played a minor role in Cooper, where the —————— 9 Two differences in particular stand out. First, while Dr. Ragusa looked only at Democratic voters to control for partisanship, Professor Ansolabehere looked at both Democratic and Republican voters. 1 App. in Cooper v. Harris, O. T. 2016, No. 15–1262, pp. 334–337. Only after calculating the percentage of black voters moved in each partisan group

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