IAS Gyan



10th April, 2021 Miscellaneous


An electoral system is defined as “the manner in which votes are translated into seats.

 Three key elements of any electoral system are:

  • District size: the number of representatives elected in one electoral district;
  • Electoral formula: by which the winner of a seat is chosen; and
  • Ballot structure: which determines whether the voter votes for a candidate or a party, and whether the voter makes a single choice or expresses a series of preferences.

 There are three main electoral system families, classified according to how they translate votes into seats (plurality/majority, mixed and proportional systems) and a fourth family, into which individual systems that do not fit in the three main families are grouped. There are 12 individual electoral systems identified within these main families.

Plurality/majority systems are based on the principle that the candidate or party with a plurality of votes (i.e., more than any other) or a majority of votes (i.e., 50 per cent plus one—an absolute majority) is declared the winner. Such a system may use single-member districts (e.g., FPTP, alternative vote or the two-round system) or multi-member districts (e.g., block vote or party block vote).

Proportional representation (PR) is the electoral system family based on the principle of translating the overall votes of a party or grouping into a corresponding proportion of seats in an elected body. For example, a party that wins 30 per cent of the votes will receive approximately 30 per cent of the seats. All PR systems require the use of multi-member districts. There are two major types of PR systems: list PR and single transferable vote (STV).

In a mixed system, voters’ choices are used to elect representatives using two different systems: one PR and one plurality/majority. There are two kinds of mixed systems: parallel systems and mixed-member proportional systems. As women’s representation on average is higher in PR systems than in plurality/majority systems, strategically designing a mixed system (for instance, electing half of the members of parliament through a PR system and the other half using a plurality/majority system) can be an effective way to increase women’s representation.

Three types of individual electoral systems—single non-transferable vote (SNTV), limited vote (LV) and Borda count (BC)—form part of a fourth electoral system family, in which the SNTV system is a multi-member-district system in which voters can cast one vote for one candidate. LV is similar to the SNTV system, but voters have more than one vote (but less than the total number of candidates, as in the block vote system).”

The principle of plurality/majority systems is simple. After votes have been cast and totalled, those candidates or parties with the most votes are declared the winners (there may also be additional conditions). However, the way this is achieved in practice varies widely.

Five varieties of plurality/majority systems can be identified:

  • First Past The Post (FPTP),
  • Block Vote (BV),
  • Party Block Vote(PBV),
  • Alternative Vote (AV), and
  • the Two-Round System (TRS).

In an FPTP system (sometimes known as a plurality single-member district system) the winner is the candidate with the most votes but not necessarily an absolute majority of the votes. When this system is used in multi-member districts, it becomes the Block Vote. Voters have as many votes as there are seats to be filled, and the highest-polling candidates fill the positions regardless of the percentage of the vote they achieve. This system—with the change that voters vote for party lists instead of individual candidates—becomes the Party Block Vote.

Majoritarian systems, such as the Alternative Vote and the Two-Round System, try to ensure that the winning candidate receives an absolute majority (i.e. over 50 per cent). Each system in essence makes use of voters’ second preferences to produce a winner with an absolute majority if one does not emerge from the first round of voting.


 The First Past The Post system is the simplest form of plurality/majority system, using single member districts and candidate-centred voting. The voter is presented with the names of the nominated candidates and votes by choosing one, and only one, of them. The winning candidate is simply the person who wins the most votes; in theory he or she could be elected with two votes, if every other candidate only secured a single vote. Along with the UK, the cases most often analysed are Canada, India, and the United States. 


The Block Vote is simply the use of plurality voting in multi-member districts. Voters have as many votes as there are seats to be filled in their district, and are usually free to vote for individual candidates regardless of party affiliation. In most BV systems, they may use as many, or as few, of their votes as they wish. The system was used in Jordan in 1989, in Mongolia in 1992, and in the Philippines and Thailand until 1997, but was changed in all these countries as a result of unease with the results it produced.

Advantages of BV

The Block Vote is often applauded for retaining the voter’s ability to vote for individual candidates and allowing for reasonably-sized geographical districts, while at the same time increasing the role of parties compared with FPTP and strengthening those parties which demonstrate most coherence and organizational ability.

Disadvantages of BV

However, the Block Vote can have unpredictable and often undesirable impacts on election outcomes. For example, when voters cast all their votes for the candidates of a single party, the system tends to exaggerate most of the disadvantages of FPTP, in particular its disproportionality. When parties nominate a candidate for each vacancy in a Block Vote system and encourage voters to support every member of their slate, this is particularly likely


Under Party Block Vote, unlike FPTP, there are multi-member districts. Voters have a single vote, and choose between party lists of candidates rather than between individuals. The party which wins most votes takes all the seats in the district, and its entire list of candidates is duly elected. As in FPTP, there is no requirement for the winner to have an absolute majority of the votes.PBV was used as the only system or the major component of the system in four countries—Cameroon, Chad, Djibouti and Singapore.

Advantages of PBV

PBV is simple to use, encourages strong parties and allows for parties to put up mixed slates of candidates in order to facilitate minority representation. It can be used to help to ensure balanced ethnic representation, as it enables parties to present ethnically diverse lists of candidates for election—and may indeed be designed to require them to do so.

Disadvantages of PBV

However, the Party Block Vote also suffers from most of the disadvantages of FPTP, and may indeed produce highly disproportional results where one party wins almost all of the seats with a simple majority of the votes.


Elections under Alternative Vote are usually held in single-member districts, like FPTP elections. However, AV gives voters considerably more options than FPTP when marking their ballot paper. Rather than simply indicating their favoured candidate, under AV electors rank the candidates in the order of their choice, by marking a ‘1’ for their favourite, ‘2’ for their second choice, ‘3’ for their third choice and so on. The system thus enables voters to express their preferences between candidates rather than simply their first choice. For this reason, it is often known as ‘preferential voting’ in the countries which use it.

 AV also differs from FPTP in the way votes are counted. Like FPTP or TRS, a candidate who has won an absolute majority of the votes (50 per cent plus one) is immediately elected. However, if no candidate has an absolute majority, under AV the candidate with the lowest number of first preferences is ‘eliminated’ from the count, and his or her ballots are examined for their second preferences. Each ballot is then transferred to whichever remaining candidate has the highest preference in the order as marked on the ballot paper. This process is repeated until one candidate has an absolute majority, and is declared duly elected. AV is thus a majoritarian system.

It is possible, but not essential, in preferential systems such as AV to require voters to number all, or most, of the candidates on the ballot paper. This avoids the possibility of votes becoming ‘wasted’ at a later stage in the count because they bear no further valid preferences. However, it can lead to an increase in the number of invalid votes, and it can sometimes give substantial importance to preferences between candidates to which the voter is indifferent or actively dislikes.

Advantages of AV

One advantage of transferring ballots is that it enables the votes of several candidates to accumulate, so that diverse but related interests can be combined to win representation. AV also enables supporters of candidates who have little hope of being elected to influence, via their second and later preferences, the election of a major candidate. For this reason, it is sometimes argued that AV is the best system for promoting centrist politics, as it can compel candidates to seek not only the votes of their own supporters but also the ‘second preferences’ of others. To attract these preferences, candidates must make broadly-based appeals rather than focusing on narrower issues.

Disadvantages of AV

Nevertheless, AV also has a number of disadvantages. First, it requires a reasonable degree of literacy and numeracy to be used effectively, and because it operates in single-member districts it can often produce results that are disproportional when compared to PR systems—or even in some cases compared with FPTP. Also, the potential of AV for promoting centrist outcomes is very dependent on underlying social and demographic conditions.


The central feature of the Two-Round System is as the name suggests: it is not one election but takes place in two rounds, often a short time apart. The first round is conducted in the same way as a single-round plurality/majority election. In the most common form of TRS, this is conducted using FPTP. It is, however, also possible to conduct TRS in multi-member districts using Block Vote (as in Kiribati) or Party Block Vote (as in Mali). A candidate or party that receives a specified proportion of the vote is elected outright, with no need for a second ballot. This proportion is normally an absolute majority of valid votes cast, although several countries use a different figure when using TRS to elect a president. If no candidate or party receives an absolute majority, then a second round of voting is held and the winner of this round is declared elected.


 The rationale underpinning all PR systems is to consciously reduce the disparity between a party's share of the national vote and its share of the parliamentary seats; if a major party wins 40 per cent of the votes, it should win approximately 40 per cent of the seats, and a minor party with 10 per cent of the votes should also gain 10 per cent of the legislative seats. This congruity between a party’s share of the vote and its share of the seats provides an incentive for all parties to support and participate in the system.

PR requires the use of electoral districts with more than one member: it is not possible to divide a single seat elected on a single occasion proportionally. There are two major types of PR system—List PR and Single Transferable Vote (STV). Proportionality is often seen as being best achieved by the use of party lists, where political parties present lists of candidates to the voters on a national or regional basis, but preferential voting can work equally well: the Single Transferable Vote, where voters rank-order candidates in multi-member districts, is another well-established proportional system.

List PR:

 In its most simple form, List PR involves each party presenting a list of candidates to the electorate in each multi-member electoral district. Voters vote for a party, and parties receive seats in proportion to their overall share of the vote in the electoral district. Winning candidates are taken from the lists in order of their position on the lists.


 STV has long been advocated by political scientists as one of the most attractive electoral systems, but its use for legislative elections has been limited to a few cases—the Republic of Ireland since 1921, Malta since 1947, and once in Estonia in 1990.

STV uses multi-member districts, and voters rank candidates in order of preference on the ballot paper in the same manner as under the Alternative Vote system. In most cases, this preference marking is optional, and voters are not required to rank-order all candidates; if they wish, they can mark only one.

After the total number of first-preference votes are tallied, the count then begins by establishing the quota of votes required for the election of a single candidate.

The result is determined through a series of counts. At the first count, the total number of first-preference votes for each candidate is ascertained. Any candidate who has a number of first preferences greater than or equal to the quota is immediately elected.

In second and subsequent counts, the surplus votes of elected candidates (i.e. those votes above the quota) are redistributed according to the second preferences on the ballot papers. The process of successive counts, after each of which surplus votes are redistributed or a candidate is eliminated, continues until either all the seats for the electoral district are filled by candidates who have received the quota, or the number of candidates left in the count is only one more than the number of seats to be filled, in which case all remaining candidates bar one are elected without receiving a full quota.

Advantages of STV

The advantages claimed for PR generally apply to STV systems. In addition, as a mechanism for choosing representatives, STV is perhaps the most sophisticated of all electoral systems, allowing for choice between parties and between candidates within parties. The final results retain a fair degree of proportionality, and the fact that in most actual examples of STV the multi-member districts are relatively small means that a geographical link between voter and representative is retained.

STV also provides a better chance for the election of popular independent candidates than List PR, because voters are choosing between candidates rather than between parties (although a party-list option can be added to an STV election; this is done for the Australian Senate).

Disadvantages of STV

The disadvantages claimed for PR generally also apply to STV systems. In addition:

  • STV is sometimes criticized on the grounds that preference voting is unfamiliar in many societies, and demands, at the very least, a degree of literacy and numeracy.
  • The intricacies of an STV count are quite complex.
  • STV, unlike Closed List PR, can at times produce pressures for political parties to fragment internally because members of the same party are effectively competing against each other, as well as against the opposition, for votes.
  • STV can lead to a party with a plurality of votes nonetheless winning fewer seats than its rivals.


Mixed electoral systems attempt to combine the positive attributes of both plurality/majority (or other) and PR electoral systems. In a mixed system, there are two electoral systems using different formulae running alongside each other. The votes are cast by the same voters and contribute to the election of representatives under both systems. One of those systems is a plurality/majority system (or occasionally an ‘other’ system), usually a single-member district system, and the other a List PR system.

There are two forms of mixed system. When the results of the two types of election are linked, with seat allocations at the PR level being dependent on what happens in the plurality/majority (or other) district seats and compensating for any disproportionality that arises there, the system is called a Mixed Member Proportional (MMP) system. Where the two sets of elections are detached and distinct and are not dependent on each other for seat allocations, the system is called a Parallel system. While an MMP system generally results in proportional outcomes, a Parallel system is likely to give results the proportionality of which falls somewhere between that of a plurality/majority and that of a PR system.

Parallel and MMP systems have been widely adopted by new democracies in Africa and the former Soviet Union.

 Under MMP systems, the PR seats are awarded to compensate for any disproportionality produced by the district seat results. For example, if one party wins 10 per cent of the vote nationally but no district seats, then it will be awarded enough seats from the PR lists to bring its representation up to 10 per cent of the seats in the legislature. Alternatively, voters may make only one choice, with the party totals being derived from the totals for the individual district candidates.

Parallel systems also use both PR and plurality/majority components, but unlike MMP systems, the PR component of a parallel system does not compensate for any disproportionality within the plurality/majority districts.

In a Parallel system, as in MMP, each voter may receive either one ballot paper which is used to cast a vote both for a candidate and for his or her party. Parallel systems have been a product of electoral system design over the last decade and a half—perhaps because they appear to combine the benefits of PR lists with those of plurality/majority (or other) representation.

Three systems do not fit neatly under any one of the above-mentioned categories. The Single Non-Transferable Vote is a multi-member-district, candidate-centred system in which voters have one vote. Limited Vote is very much like SNTV but gives voters more than one vote (however, unlike Block Vote, not as many as there are seats to be filled). Borda Count is a preferential system in single- or multi-member districts. These systems tend to translate votes cast into seats in a way that falls somewhere between the proportionality of PR systems and the results of plurality/majority systems.