Condorcet method for admin voting
From Blitzed
An overhaul of the way we conduct admin votes was discussed in December 2004/January 2005 and a Condorcet CSSD/Beatpath method was chosen. This page describes how the method is implemented here at Blitzed.
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[edit] Introduction
In the Condorcet method, admins rank their options in order of preference and every option is paired against every other to determine the option that is acceptable to the majority of admins. This system has the main advantage that it is able to handle multiple similar options.
This Condorcet method was chosen over our old voting method (simple majority), multiple stage simple majority, and Instant-runoff voting.
[edit] Example vote
In order to make things clearer an example vote will be worked out. The example vote is as follows:
- There is some question over the behaviour of an admin, and it is determined that an admin vote is necessary to decide the fate of this server. Possible options include:
- a) Do nothing.
- b) Delink the server.
- c) Change the admin of the server, or delink the server if no suitable admin can be agreed.
10 Blitzed server admins vote with their preferences as follows:
acb acb acb acb acb bca bca cab cab cab
[edit] Method
Options are paired off and wins/losses counted. For our example:
- (a) vs (b): (a) with 8 wins
- (b) vs (c): (c) with 8 wins
- (c) vs (a): tie
It is possible to indicate that you have no preference between candidates by missing them out, e.g: in a vote between (a), (b) and (c); "ab" is the same as "abc" but "a" means "I want (a) and have no preference between (b) and (c)". "" (empty vote) means "I have no preference at all" and is the same as "abstain". Options with no preference lose against all other options for pairwise contests.
If there is a set of options which are unbeaten against any other options then that set is the so-called Schwartz set and all other options are eliminated. (a) and (c) are unbeaten here so (b) is eliminated.
From the Schwartz set, the weakest defeat would be dropped. This would continue until there is only one option that remains unbeaten. However in the above example there are only two options and they tie (no defeat).
The result of the vote is a tie between (a) and (c).
[edit] Resources
- Web-based CSSD/Beatpath calculator - make sure to select "Beatpath Winner"
- Python script to calculate CSSD/Beatpath
In the web version, results for our example entered like this:
5:a>c>b 2:b>c>a 3:c>a>b
If there were votes with no preference, they would be entered like this:
5:a>b>c 1:a>b=c
This says that:
- Five voters chose "abc", one voter chose "a" ("I want (a) with no preference between (b) or (c)")