The Creative Math Behind Elections
A very interesting overview of 6 voting methods. Approval voting is kind of a cute concept… you just put a mark next to any and all candidates of whom you approve, and whoever has the most approval wins. Brilliant.
Funnily, the only one that I found confusing was my favorite voting method, Instant Runoff Voting! Does anyone know what they mean by “Mathematical models prove that ranking a candidate lower can cause that person to climb in the overall rankings.”? I’ll have to look into this further.
Instant Runoff
Promise: Voters rank the candidates, and their top picks are tallied. If that doesn’t yield a majority, the candidate with the fewest votes is dropped, and his supporters’ ballots are recounted and allocated to the second choice. The process continues until there’s a winner.Precinct: Australia, Ireland, and San Francisco
Problem: This is a strong challenger to plurality, but it isn’t flawless. It fails the monotonicity criterion - the principle that voting for your favorite candidate should always benefit that candidate. Mathematical models prove that ranking a candidate lower can cause that person to climb in the overall rankings.
detailed description of the monotonicity problem here:
http://electionmethods.org/evaluation.htm