Voting Systems

John Kilcullen
Copyright (c) 1995, 2000, R.J. Kilcullen.


In the House of Representatives we have "single-member constituencies"; in the Senate we have "multi-member constituencies" -- for Senate elections each State is one constituency, electing six (or, in a double dissolution, 12) members. House of Representatives elections are held under a Preferential Voting system, Senate elections under a Proportional Representation system. In many other countries elections are held under the "first-past-the-post" system.

Single-member and multi-member constituencies

With single-member constituencies a "gerrymander" is possible. That is, the party in power may draw the electoral boundaries so as to create some constituencies that are very safe indeed for the other party, so that some of that party's support is wasted, while making their own safe constituencies only moderately safe, thus maximising their own vote in constituencies that are winnable. In a gerrymandered system a party can win a majority of seats with less than 50% of the total popular vote (i.e. the vote of all the people, totaled over all the constituencies).

That can happen even without a deliberate gerrymander. Imagine a city in which voters for the "red" party are in overwhelming majority in the old central districts, while in the suburbs voters for the "blue" party are in a slight majority, distributed fairly evenly throughout those suburbs. Then the "blue" party has an advantage: "red" votes will be wasted in the central constituencies, which will be super-safe, and "blue" votes will not be wasted. The "blue" advantage could be overcome by making wedge-shaped constituencies each taking in some of the suburbs and some of the central districts. This would be an artificial scheme which the "blues" might regard as a gerrymander.

What criteria should the electoral commissioners use in drawing boundaries? In the above example, if they follow the usual criteria -- not dividing traditional communities, following geographical features, etc. -- the system will be biassed against the "reds". Should the electoral commissioners aim deliberately at an even balance of the parties?

Fair electoral boundaries (in the sense of no gerrymander) do not guarantee fair representation in parliament. Suppose the electoral commissioners draw up wedge-shaped constituencies, so that no constituency is safe for either party; and suppose there is a swing of support that is uniform (i.e. the movement of support from one party to another is the same in each of the wedge-shaped electorates); then the winning party will win all the seats. Just over 50% of the total popular vote would give 100% of the seats in parliament. The only reason why the opposition party has any representation in a parliament based on single-member constituencies is that swings are seldom uniform and the electoral boundaries are not drawn so as to make each seat winnable by either party.

Multi-member constituencies with proportional representation (see below) give fairer representation, but at the cost of making representatives more remote from local interests. The fact that people live dispersed through space is significant. An electoral system should not be based on the assumption that it matters very much which party people support, but that it does not matter at all where they live.

First-past-the-post, preferential voting, proportional representation

These are different methods of counting votes. (A note on terminology: a "plurality" means more votes than any of the other candidates, a "majority" means more than 50% of the votes.)

In the "first past the post" system voters put a tick or the number 1, or some other sign, beside the name of the candidate they want to vote for, and express no other preference; the candidate with the most ticks, etc., is elected, even if their share of the vote is less than 50% -- i.e. election requires a plurality but not a majority. If there are three, four, five, etc. candidates with almost equal support, then the winning candidate may get little more than one third, one quarter, one fifth, etc. of the total vote. A candidate whom most voters did not want to win may be elected. Many countries have "first-past-the-post" with single member constituencies, including Britain, Canada and the United States of America.

A similar method can be used with multi-member constituencies. If several members, say 3, are to be elected, the voters may be given only one vote, or they may be given 3 votes, or they may be allowed up to 3 votes. (The last case allows for "plumping" -- i.e. it allows voters to give one vote to their preferred candidate and not give any votes to others, thereby increasing the likelihood that their candidate will come in first.) When the votes are counted the three candidates with more votes than any of the others are elected, even if none of them gets 50%. If voters have three votes, then the party which most voters support will get all three representatives. If there are more than two parties the party that most voters do not support may win all the places. (In the United States an electoral college elects the President. All the electoral college votes for a given state (except Maine and Nebraska) go to the one Presidential candidate, even if only a narrow majority of voters in that state voted for that candidate. See here and here.)

"Preferential" voting is the system we have for the House of Representatives. In this system the voter numbers the candidates in order of preference. In elections for our House of Representatives voters must indicate an order of preference through all the candidates, even though they may not really care past the first two or three; in the "optional preferential" variant of this system a vote is valid provided at least a first preference is indicated. When the votes are counted the candidate with more than 50% of the votes is declared elected. If no candidate has more than 50% on the first count, the candidate with fewest votes is eliminated and the voting papers in that candidate's pile are reallocated to the piles of other candidates in accordance with voters' preferences, and the count is done again -- the process is repeated until some candidate gets more that 50% of the vote. This is sometimes called the "transferable vote" system: voters who support a candidate who may turn out not to have enough support to win can indicate that in that case they want their vote transferred to another stronger candidate.

The preferential voting system is supposed to give most voters the representative they prefer, or at least their second or third preference: or at any rate, they will not get the representative the majority of them want least. However, the best "compromise" candidate, the candidate who is everyone's first or second preference, may be eliminated at the first count, if that candidate happens to get the lowest number of first preferences.

A system similar to preferential voting is the "run-off" system used in France. Two polls are held on two days about a week apart. If on the first day some candidate gets more than 50% of the vote, that candidate is elected and the second poll is not held. If no candidate gets more than 50% the second vote is held, and this time the count is "first-past-the-post". Between the two votes some candidates usually withdraw and advise their supporters to vote for another candidate who has a chance of winning. In this system the "compromise" candidate is not eliminated automatically if they do not get many votes the first time; no candidate is automatically eliminated. This system can be abused; some candidates who cannot win may threaten to stay in and spoil the chances of others who could win, hoping to exact some deal. If several candidates stay in the race, this method becomes simply "first-past-the-post".

(The Pope is elected by a run-off method.)

Preferential voting is used with single-member constituencies. For multi-member constituencies its counterpart is Proportional Representation.

In the Proportional Representation (or "quota preferential") system voters indicate an order of preference (the system may be "optional preferential", and then only a first preference, or a few preferences, need be indicated). Before the votes are counted a "quota" is worked out; a candidate is elected when he or she gets the "quota" or more. Under the "Hare-Clark" system used in Australia, the quota is worked out according to the formula: (v/(n+1))+1, where "v" is the number of votes cast and "n" is the number of persons to be elected. Thus if there are 100 votes and 3 persons to be elected the quota is 100 divided by (3+1), i.e. 25, plus 1, which is 26 -- a candidate who gets 26 or more votes will be elected; no more than 3 candidates can get 26 votes, so only 3 places will be filled. (Preferential voting in a single-member constituency comes under this formula as a particular case: if one person is to be elected, the quota is 100 divided by (1+1), plus 1, which is 51 votes.) If a candidate gets more than the quota their "surplus" votes are distributed to other candidates according to the voters' preferences, so no votes are "wasted". If in the first count no candidate gets a quota, then the candidate who gets the lowest number of votes is eliminated and all their votes are distributed to other candidates according to the voters' preferences. The process continues until 3 candidates have got a quota or more.

The advantage of multi-member constituencies with "quota preferential" voting is that parliamentary representation more accurately reflects the party's support among voters. Suppose there are twice as many "red" voters as "blue", then two of the "red" party's candidates will get a quota and be elected, and so will one "blue" candidate. Also, gerrymander is more difficult: if the "reds" make some of the multi-member constituencies very safe indeed for the "blues", then in those constituencies the "blues" simply get more quotas and return more members. Also, there are no "marginal constituencies" (though there are marginal candidates, those who just get elected), so parties have no incentive to neglect some constituencies and prioritise others.

But Proportional Representation also has drawbacks: (1) It has the drawback that any Preferential system has, namely that if they do not get enough first preferences "compromise" candidates will be eliminated at an early stage of the count. (2) Because the ballot paper is complex many voters are likely to follow party how-to-vote tickets blindly. This gives great power to the party machine, which may cause or contribute to its corruption. Suppose the "blues" are sure to get 3 quotas and could possibly get 4, then the party should field at least 4 candidates: the three at the top of the how-to-vote ticket are sure to be elected, the 4th might be, the others will not. The party organisers award candidates either a sure job, a chance, or no chance, when they decide the order of the how-to-vote card. Senators or Senate candidates have to keep in with the party organisers; hence the strength of factionalism. In Australian politics one of the typical career lines is to become State Secretary (controller of the party machine), then Senator.

In our upper house elections voters who vote "above the line" thereby accept the order of preference that the party organisers have registered with the electoral office. (In 2016 the rules changed for the election of the Australian Senate to prevent parties' directing "above the line" votes to other parties. Above-the-line votes are still allocated to a party's candidates in accordance with the party's list. See here.) If the Electoral Act were amended to provide that the votes a party gets above the line had to be distributed equally among the party's candidates, then the power of the party power-brokers would be greatly reduced: voters who knew nothing in particular about the party's candidates would vote above the line, and which candidates got elected would depend on the preferences of voters who knew something favourable or unfavourable about particular candidates.

"Robson Rotation" has a similar effect. Voters who support a party but have no preferences among its candidates simply vote down the list, and their votes go equally to all its candidates. Which of the candidates get elected depends on party supporters who do have a preference among its candidates, who do not simply vote down the list. Thus the equivalent of a "primary" restricted to party supporters (viz. to voters who are actually voting for the party) is built into the election itself.


Voting systems and party systems
By a party system I mean the set of political parties that compete for power in a country at a given time. First past the post and single member constituencies (as in the UK, US, Canada) make it difficult for new parties or independents to gain a footing, so that the party system becomes more rigid (or more "stable", if you think this is a good thing). In such countries voters sometimes have to engage in "tactical voting" -- that is, voting for a larger party they do not support long-term, to fend off a possible win by a party they very much oppose. This is a set back, temporary at least, to minor parties and independents.

Related pages

Voting systems of  States and Territories
Commonwealth Electoral Act (Australia)
Single Transferable Vote
The MMP electoral system (New Zealand)
How Proportional Representation came to be adopted by the Australian Senate


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