Single Transferable Vote and Instant Runoff Voting Software
OpenSTV is open-source software for implementing the single transferable vote and other voting methods such as instant runoff voting, Condorcet voting, and approval voting. OpenSTV is the only open-source software that implements the single transferable vote exactly as used by governments, including Scotland and the City of Cambridge, Massachusetts. These methods have been extensively verified against other software and/or actual election results.
Organizations can use OpenSTV to implement their own elections. First, the organization must adopt a voting method. Second, the organization must conduct the vote, and this will most likely be done with paper ballots. Third, the ballots must be entered into the OpenSTV program. Finally, you can use OpenSTV to count the votes and determine the winners of the election.
OpenSTV will run on MS Windows, Mac OS X, and Linux. To download OpenSTV to your computer, select the download link at the top of the page. Please send questions to the email list:
openstv at googlegroups.com
I obtained a copy of the of final ballots for the Cambridge, Massachusetts City Council and School Committee elections and used OpenSTV to verify the official count.
You can download a PDF reports of the City Council election and School Committee election created using OpenSTV, and compare them to the official results at the website for the Cambridge Election commission.
Thomas Wright Hill is generally credited with inventing STV in the early 19th century. A statement of his voting rule appears in the Laws of the Society for Literary and Scientific Improvement; established in Birmingham, October the 19th, 1819.
Brian Wichmann has kindly provided a scan of this document, downloadable as a 5MB PDF. The original is available for inspection in the Birmingham Central Library (reference 62702).
The rule itself appears in section X of the bylaws:
Cambridge held its STV elections for city council and school committee last night, and since I live nearby, I decided to stop by and watch how they count the votes. Cambridge has been doing STV elections since 1941, and it shows by how organized they are. Here is my understanding of how the vote counting worked.
Cambridge uses ballots where the voters fill in bubbles with a pen to rank the candidates. Here is an example of this year's ballot.
Sequioa Voting Systems makes voting machines, e.g., the physical devices that one uses to enter votes. Historically, these voting machines are called "voting systems," which can be confusing since other people use the term "voting system" to refer to the method of counting votes, e.g., instant runoff voting.
Sequioa has recently announced that it will release an open-source voting system. Here is a quote from the press release:
There are three papers in Voting matters Issue 27, now available at the Voting matters web site:
- The paper by Joseph Durham and Peter Lindener, Moderated Differential Pairwise Tallying, considers a method of electing candidates using a preferential ballot which is quite unlike STV. The paper details the rationale behind the method, using Borda scores and Condorcet as starting points.
As with all such methods, it is difficult to convince people to use a new system, even given a detailed analysis of its effects. How do voters react to knowing that later preferences can affect the earlier ones?
