How are elections won and how would different voting methods affect the outcomes? For the September evening meeting, Usha led us through an exploration of the math behind elections.
After a few math warm-ups, we began by looking at data from past US presidential elections and shared things we noticed. The following data was provided for the 1968, 1992, and 2000 presidential elections as well as data from September 2019 Iowa Caucus-goers:
1968 Presidential Election
Richard Nixon 31,785,480
Hubert Humphrey 31,275,166
George Wallace 9,906,473
Suppose that 2/3 of Wallace supporters preferred Humphrey to Nixon, about 2/3 of Nixon supporters preferred Humphrey to Wallace, and about 2/3 of Humphrey’s supporters preferred Nixon to Wallace.
1992 US Presidential Election
Bill Clinton 43,682,624
George Bush 38,117,331
Ross Perot 19,217,213
Based on polls, experts believed that Perot’s supporters were about evenly split in their preferences for Clinton and Bush. Suppose that about 2/3 of Clinton voters preferred Perot to Bush and about 2/3 of Bush supporters preferred Perot to Clinton.
2000 Florida Presidential
George W Bush 2,912,790
Al Gore 2,912,253
Ralph Nader 97,488
September 2019 Iowa Caucus-goers
Elizabeth Warren 22%
Joe Biden 20%
Bernie Sanders 11%
Pete Buttigieg 9%
Kamala Harris 6%.
Cory Booker 3%
Amy Klobuchar 3%
Tulsi Gabbard 2%
Beto O’Rourke 2%
Tom Steyer 2%
Andrew Yang 2%.
We then looked at the following voting methods:
“Plurality” means the winner is the candidate with the most votes. You vote for only one candidate. Votes are totaled and the one with the most votes is the winner.
Runoff Systems are used to decide elections in the US. A typical runoff system requires a second election if no candidate gets a majority.
A runoff diagram uses points and arrows to show how each candidate would fair in run-offs with all of the other (p 19)
Sequential Runoff. The difference between a runoff and a sequential runoff is that in a runoff, all but the top two are eliminated at once. In a sequential runoff, only one candidate is eliminated at a time.
Pairwise Voting A practice in which the voters vote on two of the candidates at a time.
Approval Voting is a single-winner electoral system where each voter may select (“approve”) any number of candidates. The winner is the most-approved candidate.
Point Systems assign a number of points for a first-place ranking, fewer points for a second place ranking, fewer still for a third-place ranking, etc. The winner is the candidates with the highest point total.
Insincere Voting – A practice in which voters decide to vote differently from the way in which they actually feel about the candidates.
After discussing the voting systems, we paired off to explore one voting system and one data set provided.
Sophie and Audrey explored approval voting using the data provided from the September 2019 Iowa Caucus-goers.
Kevin and Eric looked at runoff voting for the same data.
Ray compared both approval and runoff methods.
Which voting system do you think best reflects the voter’s preferences? There is still plenty to explore!
