Representation Society of Australia
DEFINITION: District magnitude is the number of representatives that voters in a particular electoral district are entitled to elect. In systems that use single-member electoral districts, such as Australian's 150-member House of Representaives, the district magnitude is 1. At the other extreme are party list systems, which the PRSA opposes. In party list systems, MPs are not directly elected, and in Israel's 120-member Knesset, and the 150-member House of Representatives of The Netherlands - where the whole nation forms one single lower house electoral district - the district magnitude is equal to the number of MPs in the house.
SIZE OF THE DISTRICT MAGNITUDE: The larger the district magnitude, the smaller is the percentage quota required for election, although the actual number of votes that forms the quota becomes larger. Larger also is the expected number of candidates (all other things being equal), with a correspondingly larger and more unwieldy ballot paper, and a larger geographical area and number of electors to interact with.
New South Wales MLCs are elected from the whole State of NSW, but unlike Victoria and Western Australia, whose MLCs do not have a whole State as an electoral district, their office addresses are nearly all in Sydney (that is evident from their listed landline telephone numbers nearly all starting with '9230'). Any proportional representation system is ultimately approximate. A law of diminishing returns points to 9 being a reasonable upper value for district magnitude, so PR-STV is most workable when it uses an odd number from 5 to 9, but it could be just outside that range if a particular case, such as those just below, justified it.
AUSTRALIAN FEDERAL PARLIAMENT: Sections 7, 24, and 29 of the Australian Constitution prevent either Senate or House of Representatives electoral districts being formed out of parts of different States, so the largest electoral district in a State for either house cannot exceed the area of the State. Arrangements for coping with that limitation - as Section 128 makes a change most unlikely - have been considered in a PRSA letter to a former Australian Democrats officer. See examples of how electoral districts could be configured for the House of Representatives.
STATE AND TERRITORY LEGISLATURES: These legislatures lack the above constraints on how their electoral districts are arranged. The Tasmanian and ACT Assemblies have never used a multi-member district magnitude greater than 7 or less than their current number of 5, but the first State Upper Houses to use PR, South Australia and New South Wales, set the whole State as a single electoral district, but have MLCs elected so they serve staggered terms, resulting in district magnitudes of 11 and 21 respectively, The later adoption of PR in Western Australia and Victoria involved general elections, with much smaller district magnitudes, of 6 and 5 respectively, resulting in MLCs tending to blend their political stance with a greater focus on identification with their region compared with SA and NSW.
MUNICIPAL DISTRICT MAGNITUDES: These vary across Australia, but are at a maximum of 12 and, except for urban municipalities in Queensland, and a slowly decreasing minority of municipalities in Victoria, where the district magnitude is as low as 1, are at a minimum of 3.
HARE-CLARK: Proportional representation using the single transferable vote (PR-STV) is the only form of PR where the person elected is directly elected by the voters. Therefore the voters have ultimate control over who is elected, as in the Tasmanian and Australian Capital Territory Assemblies, which use the superior Hare-Clark electoral system. In Australia's upper houses, however, political parties' self-serving overlays of stage management and regimented voting arrangements have been imposed, and they have been very effective in reducing that control.