Approval ballot

An approval ballot,^[1] also called an unordered ballot,^[2] is a ballot in which a voter may vote for any number of candidates simultaneously, rather than for just one candidate. Candidates that are selected in a voter's ballot are said to be approved by the voter; the other candidates are said to be disapproved or rejected. Approval ballots do not let the voters specify a preference-order among the candidates they approve; hence the name unordered. This is in contrast to ranked ballots, which are ordered. There are several electoral systems that use approval balloting; they differ in the way in which the election outcome is determined:

In approval voting, there is a single winner, and he/she is the candidate with the largest number of votes.
In multiple non-transferable vote (also called block voting) there is a fixed number (say k) of winners, and they are the k candidates with the largest number of votes.
In other multiwinner approval voting systems, there is a fixed number k of winners, but they are determined by more complex procedures, in order to guarantee such properties as justified representation.

Approval ballots let the voters express dichotomous preferences.

^ Duddy, Conal (2014-07-01). "Electing a representative committee by approval ballot: An impossibility result". Economics Letters. 124 (1): 14–16. doi:10.1016/j.econlet.2014.04.009. ISSN 0165-1765.
^ Janson, Svante (2018-10-12). "Phragmen's and Thiele's election methods". arXiv:1611.08826 [math.HO].

[1] Duddy, Conal (2014-07-01). "Electing a representative committee by approval ballot: An impossibility result". Economics Letters. 124 (1): 14–16. doi:10.1016/j.econlet.2014.04.009. ISSN 0165-1765.

[:0-2] Janson, Svante (2018-10-12). "Phragmen's and Thiele's election methods". arXiv:1611.08826 [math.HO].

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