Largest remainder method

Part of the Politics series
Voting systems
Plurality/majoritarian Simple majoritarianism Limited voting Single non-transferable vote Plurality First-past-the-post Two-round Exhaustive ballot Preferential/ranked/ordinal systems Borda count Bucklin voting Condorcet methods (Copeland's, Dodgson's, Kemeny-Young, Minimax, Nanson's, Ranked pairs, Schulze) Coombs' method Instant-runoff (alternative vote) Contingent vote Oklahoma primary electoral system Cardinal/graded/rated systems Approval voting Proportional approval voting Sequential proportional approval voting Satisfaction approval voting Majority judgment Range voting
Proportional representation Party-list (Open lists, Closed lists, Local lists) Highest averages (D'Hondt, Sainte-Laguë) Largest remainder (Hare, Droop, Imperiali, Hagenbach-Bischoff) Single transferable vote (CPO-STV, Gregory, Schulze STV, Wright) Dual-member proportional representation
Mixed-member Mixed-member proportional Majority bonus system Additional member system Scorporo, Av+ Parallel voting Majoritarian representation Plurality-at-large Preferential block voting General ticket
Other Proxy voting Delegable voting Delegated voting Random selection Sortition Random ballot Social choice theory Arrow's theorem Gibbard–Satterthwaite theorem Voting system criteria Public choice theory (separate but related) Multiple Ballot Voting Cumulative voting
Politics portal

The largest remainder method (also known as Hare-Niemeyer method or as Vinton's method^[1]) is one way of allocating seats proportionally for representative assemblies with party list voting systems. It contrasts with the highest averages method.

Method

The largest remainder method requires the numbers of votes for each party to be divided by a quota representing the number of votes required for a seat (i.e. usually the total number of votes cast divided by the number of seats, or some similar formula). The result for each party will usually consist of an integer part plus a fractional remainder. Each party is first allocated a number of seats equal to their integer. This will generally leave some seats unallocated: the parties are then ranked on the basis of the fractional remainders, and the parties with the largest remainders are each allocated one additional seat until all the seats have been allocated. This gives the method its name.

Quotas

There are several possibilities for the quota. The most common are: the Hare quota and the Droop quota.

The Hare (or simple) Quota is defined as follows

The Hamilton method of apportionment is actually a largest-remainder method which uses the Hare Quota. It is named after Alexander Hamilton, who invented the largest-remainder method in 1792. It was first adopted to apportion the U.S. House of Representatives every ten years between 1852 and 1900. It is used for legislative elections in Russia (with a 7% exclusion threshold since 2007), Ukraine (5% threshold), Tunisia,^[2] Namibia and Hong Kong.

The Droop quota is the integer part of

and is applied in elections in South Africa. The Hagenbach-Bischoff quota is virtually identical, being

either used as a fraction or rounded up.

The Hare quota tends to be slightly more generous to less popular parties and the Droop quota to more popular parties. This means that Hare can arguably be considered more proportional than Droop quota^{[3][4][5][6][7]} although it is more likely to give fewer than half the seats to a list with more than half the vote.

The Imperiali quota

is rarely used since it suffers from the defect that it might result in more seats being allocated than there are available (this can also occur with the Hagenbach-Bischoff quota but it is very unlikely, and it is impossible with the Hare and Droop quotas). This will certainly happen if there are only two parties. In such a case, it is usual to increase the quota until the number of candidates elected is equal to the number of seats available, in effect changing the voting system to the Jefferson apportionment formula (see D'Hondt method).

Examples

These examples take an election to allocate 10 seats where there are 100,000 votes.

Hare quota

Droop quota

Pros and cons

It is relatively easy for a voter to understand how the largest remainder method allocates seats. The Hare quota gives an advantage to smaller parties while the Droop quota favours larger parties.^[8] However, whether a list gets an extra seat or not may well depend on how the remaining votes are distributed among other parties: it is quite possible for a party to make a slight percentage gain yet lose a seat if the votes for other parties also change. A related feature is that increasing the number of seats may cause a party to lose a seat (the so-called Alabama paradox). The highest averages methods avoid this latter paradox but since no apportionment method is entirely free from paradox,^[9] they introduce others like quota violation.^[10]

Technical evaluation and paradoxes

The largest remainder method is the only apportionment that satisfies the quota rule; in fact, it is designed to satisfy this criterion. However, it comes at the cost of paradoxical behaviour. The Alabama paradox is exhibited when an increase in seats apportioned leads to a decrease in the number of seats allocated to a certain party. In the example below, when the number of seats to be allocated is increased from 25 to 26 (with the number of votes held constant), parties D and E counterintuitively end up with fewer seats.

With 25 seats, the results are:

With 26 seats, the results are:

See also

• List of democracy and elections-related topics

References

External links

• Hamilton method experimentation applet at cut-the-knot