Editing Single transferable vote (section)

===Tactics===
{{See also|Tactical voting#Single transferable vote}}
If there are not enough candidates to represent one of the priorities the electorate vote for (such as a party), all of them may be elected in the early stages, with surplus votes being transferred to candidates with other views. On the other hand, putting up too many candidates might result in first-preference votes being spread too thinly among them, and consequently several potential winners with broad second-preference appeal may be eliminated before others are elected and their second-preference votes distributed. In practice, the majority of voters express preference for candidates from the same party in order,{{Citation needed|date=October 2010}} which minimizes the impact of this potential effect of STV.

The outcome of voting under STV is proportional within a single district to the varied opinions of voters, assuming voters have ranked their real preferences (marking their preferences to truly reflect their views). Due to the district voting mechanisms usually used in conjunction with STV, an election by STV does not guarantee proportionality across all districts. If proportionality is measured by looking at first-preference votes, the final result may appear disproportional. This is natural due to some votes being transferred from one party to another during the vote count procedure before all the seats are allocated.

In many elections, each party has their vote spread over the party's slate (if the party runs multiple candidates) so that the large parties' votes may be spread somewhat equally, and candidates of popular parties are mostly all more popular than candidates of less-popular parties. This happened in [[Cavan–Monaghan (Dáil constituency)|Cavan-Monaghan]] in the 2020 Irish general election, where Labour, PBP, Green and Aontu parties were the least popular. Their candidates were four of the five least-popular candidates in the first count and were eliminated quickly. SF, FG and FF parties were more popular{{Snd}}their candidates took the five seats{{Snd}}and candidates of those parties were already leading in the first count.<ref name="auto1">{{Cite web|url=https://data.oireachtas.ie/ie/oireachtas/electoralProcess/electionResults/dail/2020/2020-05-01_33rd-dail-general-election-results_en.pdf|title=33rd Dáil election results}}</ref>

Several methods of tactical or strategic voting can be used in STV elections but much less so than with first-past-the-post elections. In STV elections, most constituencies will be marginal, at least with regard to the allocation of a final seat. Manipulating STV requires knowledge of the contents of all the ballots, effectively only being possible after the ballots are counted; and discovering the correct votes to cast to manipulate the outcome strategically is [[NP-complete]].<ref>{{Cite web |url=https://courses.cs.duke.edu/fall06/cps296.2/stv_hard.pdf |title=Single Transferable Vote Resists Strategic Voting |access-date=27 February 2023}}</ref>

The difficulty of manipulating results under STV is credited with why it is chosen for use in part of the process of allocating the  [[Academy Awards]]. As part of the process of selecting winners for the Academy Awards, STV is used to choose nominees within each category. The Academy of Motion Picture Arts and Sciences claims that STV is preferred because "[a]lthough there are always instances in which an election procedure can be manipulated, an advantage of STV procedures is that the computations are too complex to be manipulated by a voter attempting to rank competitors of its most preferred candidate at the bottom of its preference list."<ref>{{Cite web |url=https://www.whydomath.org/node/voting/academy_awards.html |title=Why Do Math? |website=www.whydomath.org}}</ref>

STV satisfies the [[majority-rule principle]] in that the winners taken together are supported by a majority of the valid votes cast in the district. Variants like [[Schulze STV]] and [[CPO-STV]] also do.