Droop quota

The Droop quota is the quota most commonly used in elections by the method of communicable Einzelstimmgebung (STV). Sometimes it is also used in elections by proportional representation with highest average method. In STV elections, the quota is the minimum number of votes that must obtain a candidate to be elected. All votes received by a candidate in excess of quota, be transferred to other candidates, provided that the voters have given their preference in consequence more candidates. The Droop quota in 1868 by the English lawyer and mathematician Henry Richmond Droop ( 1831-1884 ) developed as a replacement for the earlier Hare quota.

Nowadays, the Droop quota is used in almost all STV elections; these include the STV variants in the Republic of Ireland, Northern Ireland, Malta and Australia. The Droop quota is similar to the simpler Hagenbach -Bischoff quota, which is sometimes also referred to as " Droop quota ".

• = total number of valid votes cast at an election valid votes
• = Total number of seats to be filled at the election seats

The extra parentheses are true from a mathematical point of view, strictly speaking, not necessary, but are often still set to make the formula for non-mathematicians clear. If the quota is not calculated in the correct order, an incorrect result will come out.

Mathematically, the formula can best be expressed as:

The square brackets indicate that must be rounded. In other words, the Droop quota is the smallest integer greater than votes / (seats 1).

The Droop quota is the minimum number of votes that will ensure that any candidate who achieves these votes is actually selected. If the ratio is less, it could happen that more candidates are declared elected than ever seats are up for grabs.

If only one seat to be filled, STV is the same as instant - runoff voting. The droop rate then corresponds to an absolute majority of votes.

• Election procedures