A report on Condorcet method

Example Condorcet method voting ballot. Blank votes are equivalent to ranking that candidate last.
sample ballot for Wikimedia's Board of Trustees elections

Election method that elects the candidate who wins a majority of the vote in every head-to-head election against each of the other candidates, that is, a candidate preferred by more voters than any others, whenever there is such a candidate.

- Condorcet method
Example Condorcet method voting ballot. Blank votes are equivalent to ranking that candidate last.

33 related topics with Alpha

Overall

Countries using first-past-the-post for legislatures.

Electoral system

11 links

Electoral systems map.svg or sole (unicameral) house of national legislatures, .Majoritarian system, single-winner districts

Electoral systems map.svg or sole (unicameral) house of national legislatures, .Majoritarian system, single-winner districts

Countries using first-past-the-post for legislatures.
Countries by type of proportional system

Ranked systems include Bucklin voting, the various Condorcet methods (Copeland's, Dodgson's, Kemeny-Young, Maximal lotteries, Minimax, Nanson's, Ranked pairs, Schulze), the Coombs' method and positional voting.

In IRV for a polarized election between left, right, and center, the votes for B are not wasted, but the consensus candidate (B) is not elected

Instant-runoff voting

12 links

Type of ranked preferential voting method.

Type of ranked preferential voting method.

In IRV for a polarized election between left, right, and center, the votes for B are not wasted, but the consensus candidate (B) is not elected
Example of a full preferential ballot paper from the Australian House of Representatives
Flowchart of Instant Runoff Voting
The Australian Electoral Commission holding a blind ballot to determine the order of candidates on the ballot paper, 2004
Top-two IRV
175x175px
161x161px
141x141px

James Green-Armytage tested four ranked-choice methods, and found the alternative vote to be the second-most-resistant to tactical voting, though it was beaten by a class of AV-Condorcet hybrids, and did not resist strategic withdrawal by candidates well.

Typical counting process of a single seat Ranked Choice Voting election, developed by William Robert Ware.

Ranked voting

10 links

The term ranked voting (also known as preferential voting or ranked choice voting) refers to any voting system in which voters rank their candidates (or options) in a sequence of first or second (or third, etc.) on their respective ballots.

The term ranked voting (also known as preferential voting or ranked choice voting) refers to any voting system in which voters rank their candidates (or options) in a sequence of first or second (or third, etc.) on their respective ballots.

Typical counting process of a single seat Ranked Choice Voting election, developed by William Robert Ware.

Methods with this property are known as Condorcet methods.

140px

Schulze method

8 links

Electoral system developed in 1997 by Markus Schulze that selects a single winner using votes that express preferences.

Electoral system developed in 1997 by Markus Schulze that selects a single winner using votes that express preferences.

140px
Sample ballot for Wikimedia's Board of Trustees elections

The Schulze method is a Condorcet method, which means that if there is a candidate who is preferred by a majority over every other candidate in pairwise comparisons, then this candidate will be the winner when the Schulze method is applied.

Smith set

6 links

Smallest non-empty set of candidates in a particular election such that each member defeats every candidate outside the set in a pairwise election.

Smallest non-empty set of candidates in a particular election such that each member defeats every candidate outside the set in a pairwise election.

The Condorcet winner, if one exists, is the sole member of the Smith set. If weak Condorcet winners exist then they are in the Smith set.

Mutual majority criterion

6 links

Criterion used to compare voting systems.

Criterion used to compare voting systems.

All Smith-efficient Condorcet methods pass the mutual majority criterion.

140px

Borda count

4 links

Family of positional voting rules which gives each candidate, for each ballot, a number of points corresponding to the number of candidates ranked lower.

Family of positional voting rules which gives each candidate, for each ballot, a number of points corresponding to the number of candidates ranked lower.

140px
An election under the Borda count

In this respect, it is the same as elections under systems such as instant-runoff voting, the single transferable vote or Condorcet methods.

Independence of irrelevant alternatives

6 links

Axiom of decision theory and various social sciences.

Axiom of decision theory and various social sciences.

In collective decision making contexts, the axiom takes a more refined form, and is mathematically intimately tied with Condorcet methods, the Gibbard–Satterthwaite theorem, and the Arrow Impossibility theorem.

A first-past-the-post ballot for a single-member district. The voter must mark one (and only one).

First-past-the-post voting

4 links

In a first-past-the-post electoral system (FPTP or FPP; formally called single-member plurality voting (SMP) when used in single-member districts, or (informally) choose-one voting in contrast to ranked voting or score voting ), voters cast their vote for a candidate of their choice, and the candidate who receives the most votes wins (even if the top candidate gets less than 50%, which can happen when there are more than two popular candidates).

In a first-past-the-post electoral system (FPTP or FPP; formally called single-member plurality voting (SMP) when used in single-member districts, or (informally) choose-one voting in contrast to ranked voting or score voting ), voters cast their vote for a candidate of their choice, and the candidate who receives the most votes wins (even if the top candidate gets less than 50%, which can happen when there are more than two popular candidates).

A first-past-the-post ballot for a single-member district. The voter must mark one (and only one).
Countries that primarily use a first-past-the-post voting system for national legislative elections
600x600px
Regional Parties achieve proportionally more seats than their vote share. Votes (left) v Seats (right) 2019 UK general election with Conservative and Labour removed.
A graph showing the difference between the popular vote (inner circle) and the seats won by parties (outer circle) at the 2015 UK general election

Examples include preferential voting systems, such as instant runoff voting, as well as the two-round system of runoffs and less tested methods such as approval voting and Condorcet methods.

Stenciling on a Parisian sidewalk ahead of the first round of the 2017 French presidential election invoking "votez utile" (tactical voting) as a reason for voters to vote for François Fillon instead of Emmanuel Macron

Tactical voting

5 links

Undesirable outcome.

Undesirable outcome.

Stenciling on a Parisian sidewalk ahead of the first round of the 2017 French presidential election invoking "votez utile" (tactical voting) as a reason for voters to vote for François Fillon instead of Emmanuel Macron

Burying: A voter insincerely ranks an alternative lower in the hopes of defeating it. For example, in the Borda count or in a Condorcet method, a voter may insincerely rank a perceived strong alternative last in order to help their preferred alternative win.