Would tactical voting end under AV?

Campaigners for a YES vote in the referendum argue that voters would no longer need to vote tactically for candidates in elections.

'Yes to fairer votes': "AV simply eliminates the need for [tactical voting]. Why should we have to abandon the party we actually support, to prevent the party we least support getting in? The dilemma facing millions of voters is often characterised as the choice between 'voting with your head or your heart'. AV allows people to do both."

'No 2 AV': "AV wouldn't eliminate tactical voting, it would reinvent it. Under AV, the challenge comes in working out the order in which candidates are eliminated, and ordering your preferences accordingly."

Facts

If AV is adopted by the UK after the referendum, people will not need to vote tactically for their first choice candidate.

However, when choosing how to rank the rest of the candidates (and the parties they represent) on their ballot paper, people would be able to put the candidates in an order that influences who would win if their favourite candidate loses. In practice, they would rank lowest the candidate (and party) that is most likely to beat their favoured candidate.

By doing this, if the person's favourite candidate (and party) has not won in their constituency, their vote, by being transferred to another less favoured candidate, will still count against their closest rival candidate (and party).

Context

Under the current First Past the Post system, people will often vote tactically for a candidate that they think has a better change of winning then their preferred candidate, so as to keep out a candidate they don't want to win.

Research reported by the British Academy (the UK's national academy for the humanities and social sciences), indicates that 15 per cent of people voted for a party other than their most preferred in the 2005 general election.

The report goes on to say: "Of those whose first choice was neither Conservative nor Labour, 45% voted for a party other than their most preferred; and of those whose first choice was other than Conservative, Labour or Liberal Democrat, only 21% voted for their most preferred party."

Under AV there would be no technical reason for voting tactically for your most preferred candidate.

However, according to the Constitution Society briefing paper, when it comes to ranking your next preference candidates, in Australia, which uses AV, tactical voting has become very important.

They say: "the evidence from Australia is that voting in AV elections is in general highly 'tactical' since it is necessary to place the candidates in a very specific order of preference to maximise the chances of any particular favoured candidate. Tactical voting does not disappear under AV; instead its arithmetic becomes more complex."

In Australia, political parties often publishe lists that tell voters how to rank candidates to give their party the best chance of winning.