Voting system for elections

[Ian Jackson]

Barak A. Pearlmutter writes ("Re: Voting system for elections"):
> It seems like a few people seem to find the argument for RRV
> convincing, and no one has objected.

I feel the need to repost here, an article I posted to spi-private on
the 4th of August:

From: Ian Jackson <ijackson at chiark.greenend.org.uk>
To: 
Cc: spi-private at lists.spi-inc.org
Subject: Re: [Spi-private] SPI board election method, reanalysis of 2016
 election
Date: Thu, 4 Aug 2016 02:15:57 +0100

[ Someone wrote asking for a: ]
> [ detailed set of analysis criteria of multi-winner voting systems ]
[ (quote redacted -iwj 16.8.16) ]

SPI should not be in the business of detailed analysis of voting
systems, let alone the development of novel voting systems.  Nor
should SPI adopt a system which is highly unusual.

There is only one multi-winner proportional voting system that makes
sense for SPI [1] and has nontrivial adoption in the world at large.
That system is STV.

  https://en.wikipedia.org/wiki/Proportional_representation

[1] There are a handful of other common proportional multi-winner
systems, including Additional Member systems, and party list PR, but
they are obviously inappropriate for us.

The right direction for this conversation is a discussion of which
other respected institution's specific set of STV rules (answers to
the edge cases) we should adopt.  We would like one which has a clear
description, from an authoritative source.

Ideally we want a variant of which there are already one or more
computerised implementations.  (Even if we end up writing our own
computer implementation, an existing program will provide a useful
check and perhaps even come with some test vectors.)


Having done another set of searches I would suggest that we should
adopt Scottish STV.  That is, the STV which is used in Scotland to
elect local councils.  Here it is laid out in the legislation:
  http://www.legislation.gov.uk/ssi/2007/42/schedule/1/part/III/crossheading/counting-of-votes/made
The rules on actual counting are paragraphs 45-52.
I also found this detailed description with examples:
  http://www.votingmatters.org.uk/RES/STV-WIGM.pdf

Allegedly this is implemented in OpenVote:
  https://packages.debian.org/jessie/openstv
  https://github.com/OpenTechStrategies/openstv
(now taken proprietary but the Free version remains available,
including version 1.6 in Debian.)

Thus this system has a clear and authoritative statement of the rules,
and seems to have at least one computerised implementation.


Or we could consider following the lead of the Apache Software
Foundation.  They use a Meek variant of STV and their page here
suggests that they have found at least two implemnetations (although
the fact that they've forked one of them isn't encouraging):
  https://wiki.apache.org/general/BoardVoting

I haven't found (so far) a clear statement of the rules, in prose.
Wikipedia suggests that New Zealand uses a version of Meek STV (and
that Stack Exchange does too for some purposes), but I'm not sure if
they're the same.

I also found this list of tools:
  http://www.accuratedemocracy.com/z_tools.htm


[ irrelevant section from -private deleted -iwj 16.8.16 ]

Ian.

-- 
Ian Jackson <ijackson at chiark.greenend.org.uk>   These opinions are my own.

If I emailed you from an address @fyvzl.net or @evade.org.uk, that is
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