Quota
A quota is a number of votes (obtained by formula) often relevant to deciding who wins and how ballots are evaluated or modified in "proportional representation" voting methods]].
The two main quotas that will be described here are the "Hare quota" and the "Droop quota".
Hare quota
The "Hare quota" (also known as the "simple quota") is a formula used under some forms of the Single Transferable Vote (STV) system and the largest remainder method of party-list proportional representation. In these voting systems the quota is the minimum number of votes required for a party or candidate to capture a seat, and the Hare quota is the total number of votes divided by the number of seats.
The Hare quota is the simplest quota that can be used in elections held under the STV system. In an STV election a candidate who reaches the quota is elected while any votes a candidate receives above the quota are transferred to another candidate.
The Hare quota was devised by Thomas Hare, one of the earliest supporters of STV. In 1868, Henry Richmond Droop (1831–1884) invented the Droop quota as an alternative to the Hare quota, and Droop is now widely used, the Hare quota today being rarely used with STV.
Droop quota
The "Droop quota" is the quota most commonly used in elections held under the single transferable vote (STV) system. It is also sometimes used in elections held under the largest remainder method of party-list proportional representation (list PR). In an STV election the quota is the minimum number of votes a candidate must receive in order to be elected. Any votes a candidate receives above the quota are transferred to another candidate. The Droop quota was devised in 1868 by the English lawyer and mathematician Henry Richmond Droop (1831–1884) as a replacement for the earlier Hare quota.
Today the Droop quota is used in almost all STV elections, including the forms of STV used in India, the Republic of Ireland, Northern Ireland, Malta and Australia, among other places. The Droop quota is very similar to the simpler "Hagenbach-Bischoff quota", which is also sometimes loosely referred to as the 'Droop quota'.