Editing Strategic voting (section)

{{Short description|Choosing a candidate other than preferred to undercut a less desired one}}
{{Use dmy dates|date=May 2020}}
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'''Strategic''' or '''tactical voting''' is voting in consideration of possible ballots cast by other voters in order to maximize one's satisfaction with the election's results.<ref>{{cite book |last=Farquharson |first=Robin |url=https://books.google.com/books?id=fIMHAQAAMAAJ |title=Theory of Voting |publisher=Blackwell (Yale U.P., U.S.) |year=1969 |isbn=978-0-631-12460-3}}</ref> 

[[Gibbard's theorem]] shows that no voting system has a single "always-best" strategy, i.e. one that always maximizes a voter's satisfaction with the result, regardless of other voters' ballots. This implies all voting systems can sometimes encourage voters to strategize. However, weaker guarantees can be shown under stronger conditions. Examples include [[Single-peaked preferences|one-dimensional preferences]] (where the [[Median voting rule|median rule]] is strategyproof) and [[dichotomous preferences]] (where [[approval voting|approval]] or [[score voting]] are strategyproof).

With large electoral districts, [[Electoral list|party list]] methods tend to be difficult to manipulate in the absence of an [[electoral threshold]]. However, biased [[Apportionment (politics)|apportionment methods]] can create opportunities for strategic voting, as can small electoral districts (e.g. those used most often with the [[single transferable vote]]). Proportional representation systems with small districts often involve large-scale [[vote management]] operations, which are common in countries using [[Single transferable vote|STV-PR]] such as [[Republic of Ireland|Ireland]].