Runoff voting election systems

Runoff voting is a family of election systems whose goal is to select a member with majority support, and where if necessary in successive stages candidates are dropped off to concentrate the votes behind a narrower field until someone has a majority of votes.

Runoff voting is only used to elect a single member.

Two main methods are used - either voters vote an additional time or in the first vote, voters mark preferential ballots, enabling ballots to be transferred.

As well, sometimes only two rounds of voting or vote counting is done; other systems allow numerous rounds of voting or counting to determine the winner.

Those two considerations produce four combinations.

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Use of runoff voting election systems in Canadian history:

Canada has used Instant-Runoff Voting (IRV) in AB, MB and BC.

Two Round System (TRS) has not been used in Canada government elections

Exhaustive ballot is used to elect party leaders or candidates in contested nomination battles in Canada, but not in Canadian gov't elections.

Contingent Voting has not been used in Canada gov't elections but has been used in UK city elections.

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