More Election Graphs

Following up on my instant fame as an guest author, here are two more graphs from the Chapel Hill Town Council election results. The first is a mosaic plot, which is close to what Mark Chilton was suggesting, I think. For each cell, the width represents the votes in that precinct, and the height represents the percentage in that precinct that voted for the candidate, so the area shows the number of votes for that candidate in that precinct. Precincts are alphabetical; candidates are in order of overall finish. Unfortunately, I couldn’t sort each column differently, as Mark suggested, so it’s not clear who “won” each precinct. Click graph for larger version.

Chapel Hill Town Council Results by Candidate

The second graph is more statistically relevant (ignoring the fact that the “Absentee” early voting precinct is not really comparable to the other geographical precincts). Each box plot summarizes the percentage outcomes for a given candidate in all the precincts. Assuming a normal (bell-curve) distribution, points outside the “whiskers” of the box plot are likely to be outliers affected by factors other than random variation. (Testing for normality indicates that only the Cutson and Baker results do not follow a normal distribution.)

Chapel Hill Town Council Results by Candidate

I labeled the outliers, though the Northside and Lincoln labels overwrite each other in the Thorpe column. The box plot outliers show Mason Farm as significant for Raymond, though it was not noticeable from the overlay line plot since that precinct had so few votes.

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