The Supplementary Vote is similar in method and purpose to the Alternative Vote, the key difference being that, under SV, voters are limited to indicating a first and second preference. Where candidates receive more than a half of first preference votes cast on the first count they are deemed elected. If not, all but the top two candidates are eliminated and their second preferences redistributed. The candidate with the greatest share of the resultant vote is elected - in the majority of cases, but not necessarily, this will be with more than half of the votes cast. As with the Alternative Vote the main objective of the Second Ballot system is to increase the chances of a candidate being elected on an absolute majority of the vote.
Voting takes place on two separate days.
If any one candidate fails to achieve an absolute majority after the first ballot a second ballot takes place. Where more than two candidates are allowed to progress to the second ballot a majority result cannot necessarily be guaranteed but, typically, candidates not performing well in the first ballot will withdraw and throw their support behind a candidate with a better chance of winning. The rationale of list systems is to translate directly a party's share of the vote into an equivalent proportion of seats in parliament. Voters are to able to rank as many candidates, both within parties and across different parties, as they wish in order of preference. Any of those candidates who reach a certain quota are deemed to have been elected.