On 5th May 2011 the UK will be holding a referendum on whether to adopt the Alternative Vote voting system for electing Members of Parliament to the House of Commons.
The Alternative Vote (AV) is very much like First-Past-the-Post (FPTP). Like FPTP, it is used to elect representatives for single-member constituencies, except that rather than simply marking one solitary ‘X’ on the ballot paper, the voter has the chance to rank the candidates on offer.
The voter thus puts a ‘1’ by their first-preference candidate, and can continue, if they wish, to put a ‘2’ by their second-preference, and so on, until they don’t care anymore or they run out of names. In some AV elections, such as most Australian elections, electors are required to rank all candidates. In the UK you won’t have to rank all the candidates. You can stop after your first preference if you like and, if you do, that’s just like voting using First Past the Post.
If a candidate receives a majority of first-preference votes (more people put them as number one than all the rest combined), then they are elected.
If no candidate gains a majority on first preferences, then the second-preference votes of the candidate who finished last on the first count are redistributed. This process is repeated until someone gets over 50 per cent.
You can see a worked example here.
The Alternative Vote is often called Instant Run Off Voting. Ideally, you would want to have multiple rounds of elections, like they do in France or the United States. with a fresh election each time the lowest polling candidate was knocked out. This would be very time consuming and expensive. The Alternative Vote System tries to get the same effect as many rounds of voting by using preferences. Preferences are just instructions to the counters of the election to transfer your vote to where it helps influence the decision of the election, according to your wishes.
Multiple rounds of voting are used every week in programs like Strictly Come Dancing or the X-Factor and the Alternative Vote is a way to compress all the information from voters you get in a 16 week series into one ballot paper.
If your first preference candidate remains in the election until the final round your vote stays with her until the final round. If your favourite candidate is knocked out, your vote is transferred to your next favourite candidate. This helps make the decision about which of the most popular candidates should be elected.
Depending on how you look at it everyone gets one vote which is transferrable or everyone gets one vote in each round. Everyone gets the same, and no one gets more votes than anyone else and this has been decided in court, and you can read the full decision.
Other Voting Systems are Available
There are two key aspects to consider when thinking about voting systems. They are Proportionality and Preferentiality.
Proportionality means how much or how little do the number of seats in Parliament a Party wins reflect the percentage of their vote. Our current system is a winner takes all system. A Party could win every seat with a third of the vote and have every Member of Parliament. In Scotland, we use the Additional Member System, this is more proportional. You still vote with an X but you do so in a large multi-member constituency and MSP’s are elected in proportion to the votes cast for their Party list.
Preferentiality means does the voter get to rank candidates in the order they like them or do they have to make one choice, and mark it with an illiterate X. The Alternative Vote system is a fully preferential system. You can, if you want, rank all the candidates but you don’t have to. The system used in London for Mayoral elections is called the Supplementary Vote system. Here, you vote for your favourite candidate and can indicate your second favourite candidate. It is partially preferential.
A third thing to consider is the number of the Members of Parliament a constituency returns. You can have a constituency with 1 Member, like we do for Westminster, a constituency with many members, like a Scottish region for Holyrood elections, or you can make the whole country one big constituency.
A system like the Single Transferrable Vote, used in Ireland for their Parliamentary elections is both Proportional and Preferential.
The Jenkins Commission on electoral reform thought that the Alternative Vote was the best voting system to use if you wanted to elect a single person to one post, like a single constituency MP to the office of Member of Parliament.
The diagram below shows some common voting systems in relation to each other.
Some of the advantages of the Alternative Vote System are that is ends wasted votes, makes Members of Parliament Work Harder for You and Ends Jobs for Life. Other people see other advantages, including the Yes to Fairer Votes Campaign. You can also read about some of the disadvantages of First Past the Post here
Other briefing notes are available
This is my view on how the Alternative Vote system works. You can see what the NHS have to say about the Alternative Vote voting system , or the Electoral Reform Society, or Wikipedia or the Jenkins Committee or the LSE.