Alternative Vote
A preferential, plurality-majority system used in single-member districts in which voters use numbers to mark their preferences on the ballot paper. A candidate who receives over 50% of first-preferences is declared elected. If no candidate achieves an absolute majority of first-preferences, votes are re-allocated until one candidate has an absolute majority of votes cast.
Block Vote (BV)
A majority-plurality system used in multi-member districts in which electors have as many votes as there are candidates to be elected. Voting can be either candidate-centred or party-centred. Counting is identical to a First Past the Post system, with the candidates with the highest vote totals winning the seat(s).
First Past the Post (FPTP)
The simplest form of plurality-majority electoral system, using single-member districts, a categorical ballot and candidate-centred voting. The winning candidate is the one who gains more votes than any other candidate, but not necessarily a majority of votes.
List Proportional Representation (List PR)
In its most simple form List PR involves each party presenting a list of candidates to the electorate, voters vote for a party, and parties receive seats in proportion to their overall share of the national vote. Winning candidates are taken from the lists.
Mixed Member Proportional (MMP)
Systems in which a proportion of the parliament (usually half) is elected from plurality-majority districts, while the remaining members are chosen from PR lists. Under MMP the PR seats compensate for any disproportionality produced by the district seat results.
Parallel System
A Proportional Representation system used in conjunction with a plurality-majority system but where, unlike MMP, the PR seats do not compensate for any disproportionality arising from elections to the plurality-majority seats.
Single Non-Transferable Vote (SNTV)
A Semi-Proportional system which combines multi-member constituencies with a First Past the Post method of vote counting, and in which electors have only one vote.
Single Transferable Vote (STV)
A preferential Proportional Representation system used in multi-member districts. To gain election, candidates must surpass a specified quota of first- preference votes. Voters' preferences are re-allocated to other continuing candidates if a candidate is excluded or if an elected candidate has a surplus.
Two-Round System (TRS)
A plurality-majority system in which a second election is held if no candidate achieves an absolute majority of votes in the first election.
