Ranked voting
The term ranked voting, also known as preferential voting or ranked-choice voting, pertains to any voting system where voters indicate a rank to order candidates or options—in a sequence from first, second, third, and onwards—on their ballots. Ranked voting systems vary based on the ballot marking process, how preferences are tabulated and counted, the number of seats available for election, and whether voters are allowed to rank candidates equally.
Ranked voting systems are opposed to cardinal voting methods, which allow voters to indicate how strongly they support different candidates (e.g. on a scale from 0-10). Cardinal ballots provide more information than ordinal ballots and as a result, they are not subject to many of the problems in ranked-choice voting (such as Arrow's impossibility theorem).
The most commonly-used example of a ranked-choice system is the familiar plurality voting rule, which gives one "point" (vote) to the candidate ranked first, and zero points to all others (making additional marks unnecessary). This is an example of a positional system, a system that assigns points to candidates based on their ranking in the ordering. Another example (Dowdall's method) assigns 1, 1⁄2, 1⁄3... points to the 1st, 2nd, 3rd... candidates on each ballot. In addition, some countries elect policymakers by instant-runoff voting, a staged variant of the plurality system.
In the US, the term ranked-choice voting is most commonly used by organizations like FairVote and RepresentUs to refer to instant-runoff voting or single transferable vote. However, it has also been used for other ranked voting systems.[1]
Several other voting methods provide alternatives to the methods described above, each with unique characteristics: