Exhaustive ballot
Under the exhaustive ballot the elector casts a single vote for his or her chosen candidate.
The exhaustive ballot is similar to the two-round system but with key differences.
Because voters may have to cast votes several times, the exhaustive ballot is not used in large-scale public elections.
The exhaustive ballot is currently used, in different forms, to elect the members of the Swiss Federal Council, the First Minister of Scotland, the President of the European Parliament, and speakers of the House of Commons of Canada, the British House of Commons and the Scottish Parliament.
Formerly, the Knesset used the exhaustive ballot system to elect the President and the State Comptroller of Israel.
In each round of an exhaustive ballot the voter simply marks an 'x' beside his or her favourite candidate.
When this occurs one of the two must achieve an absolute majority provided there are an odd number of valid votes cast.
Because, at most, it requires voters to return to the polls only once, the two-round system is considered more practical for large public elections than the exhaustive ballot, and is used in many countries for the election of presidents and legislative bodies.
[citation needed] Under the exhaustive ballot this tactic, known as "compromising", is sometimes unnecessary because, even if the voter's first choice is unlikely to be elected, she will still have the opportunity to influence the outcome of the election by voting for more popular candidates once her favourite has been eliminated.
Although the exhaustive ballot is designed to avoid "compromising" the tactic is still effective in some elections.
The compromising tactic is sometimes effective because the exhaustive ballot eliminates candidates who are unpopular in early rounds, who might have had sufficient support to win the election had they survived a little longer.
The exhaustive ballot is also vulnerable to the tactic of "push over", where voters vote tactically for an unpopular "push over" candidate in one round as a way of helping their true favourite candidate win in a later round.
[citation needed] The "push over" tactic requires voters to be able to reliably predict how others will vote.
Instant-runoff voting is less susceptible to this tactic, as voters cannot change their first preference in successive rounds.
If a large majority of Apple Pie supporters had voted for Ice Cream then the "push over" tactic would have backfired, leading to the election of Ice Cream, which Fruit partisans like even less than Apple Pie.
The exhaustive ballot is vulnerable to strategic nomination for the same reasons that it is open to the voting tactic of "compromising".
In IRV the electorate votes only once, so candidates must make the judgement of whether or not to participate in an election before the poll, and before even one round of counting has occurred.
The exhaustive ballot encourages candidates to appeal to a broad cross-section of voters.
