Difference between revisions of "Ballot"
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*Rate/score the candidates (this one is a 4 out of 5, that one is a 2 out of 10, etc.)
With all ballot types, it is generally assumed that unmarked/unranked/unrated candidates are considered worse than all marked candidates, and that the voter has no preference between any of them.
== Ballot types ==
[[Voting system]]s that use a ratings ballot include [[Score voting]], [[Instant Runoff Normalized Ratings|instant runoff normalized ratings]], and [[cardinal pairwise]].
Two rated ballots that use different scales can be converted to each other. For example, if one voter gave a candidate a 5 out of 10 and another voter gave a candidate a 3 out of 7, the 5 out of 10 can be interpreted as a 3.5 out of 7, and the 3 out of 7 as a 4.2857 out of 10. In general, all rated ballots can be thought of as approximations of (and transformable into) a scale from 0 to 1 (or 0% to 100%), with 0 being no support and 1 being full support.
* Ranked ballots are often shown as:
<blockquote>Alicia>Eileen>Brandon=Charlie=David</blockquote>meaning "Alicia is better than Eileen, Eileen is better than any of (Brandon, Charlie, David) and Alicia is also better than any of (Brandon, Charlie, David)" or
This table shows that generally speaking, a rated ballot (with enough scores/gradations) without an approval threshold provides the most information of any ballot type (except possibly Approval ballots, since
A ranked ballot can be (at least partially) reconstructed from any of the other three ballot types i.e. if a voter scored one candidate higher than another (or marked one candidate but not another), then it is known for certain that that voter would also rank that candidate higher than the other. This is because ranking is based on [[pairwise preference]]<nowiki/>s, which is what all ballot types seek to offer at least partially.
== Slot ==
A slot or preference-level is a tier in which candidates may be placed, such that they are treated as preferred more than any candidate in a lower tier, less than any candidate in a higher tier, and equally to any candidate in the same level. Approval and choose-one ballots offer two slots (supported or not supported), while rated and ranked ballots tend to offer more. Note that the ballot paper need only allow voters to mark one less slot than the number of slots the voter is meant to be able to mark, if unmarked candidates are assumed to be in the lowest slot. For example, an Approval ballot doesn't usually let voters explicitly mark/indicate who they don't approve of, since this is implicit when observing the candidates the voter didn't mark as approved.
When there are two or fewer preference levels than the number of candidates, voters are forced to compress their preferences, because of the [[w:pigeonhole principle]]. See [[Compromising]]-compression for how this can also be done by strategic voters.
This section explains how to actually allow voters to write/provide the information contained in each ballot type i.e. how a ranked ballot might look and be like, a rated ballot, etc.
When filling out a ranked ballot, often voters are either allowed to write the rank numbers next to each candidate, or they are allowed to bubble it in like so:
Each voter bubbles in which rank they want to put each candidate at.
Note that with a ranked ballot, only (number of candidates - 1) ranks need be provided (if unranked candidates are assumed to be ranked last); this is because even if the voters indicates a preference between their (number of candidates - 1) favorite candidates and uses up all of their available ranks, the last candidate they didn't rank will be assumed to be ranked last.
With a rated ballot, again, either the score can be written next to each candidate, or the voter can bubble it in like so:
== Preference information ==
The different ballot types collect different types of preference data:
1st choice information is collected by choose-one and ranked ballots, and is used mostly in [[FPTP]], [[IRV]], and [[:Category:FPTP-based voting methods|Category:FPTP-based voting methods]]. It is often associated with the [[majority criterion]].
Approval and scored preferences are used in [[rated method]]<nowiki/>s. Note that because there is no zero-sum nature to these preferences, it is not always possible to tell, for a set of candidates, which of them a voter supported and to what degree, solely from the vote totals i.e. if A gets 30 approvals and B 20, then there can be anywhere from 30 to 50 voters in the election. Generally, this information is indicated using [[approval rating]]<nowiki/>s. The other way of doing so, which is showing the candidate's point total as a % of all points received by all candidates, can be less informative, since it doesn't as clearly indicate the % of voters who support each candidate (both measures are equivalent when only looking at 1st choices).
It's important to keep in mind that voters may be incentivized to show or not show weak preferences between candidates based on ballot type. For example, a voter who thinks candidate A is a 10/10 and candidate B is a 9/10 may rank the two candidates equally or approve both of them on ranked or Approval ballots, respectively, in order to avoid exaggerating their preference between the two. So sometimes converting between one ballot type to another involves losing some of this information.
* [[Blank Ballot Criterion]]
== External links ==