Wasted votes: Difference between revisions

The number of wasted votes is equal to number of votes in the largest possible set of votes such that for any possible subset of votes in this set, removing those votes cannot change the election result. (footnote 1)

However this definition does have it's limitations: in voting methods that do not pass the participation criterion, such participation failures can drastically deflate the tally of the number of wasted votes. Example: consider the fallowing voting method: voters cast single preference votes and if there are an odd number of votes cast, the candidate with the most votes wins, otherwise the candidate with the 2nd most votes wins. Under this definition of wasted votes, there are no wasted votes under this method because every vote changes the winner. However not every vote changes the winner in a way that benefits the voter who casted it, and if a voter casts a vote that worsens the election result from their perspective, then they might as well not even castedcast that vote to begin with.

Note that for methods that allow voters to omit preferences between candidates, calculating this metric exactly (footnote 12) requires knowing not just all of the votes used in the election to calculate, but also the preferences of all of the voters casting those votes. This means that this metric is no-longer defined by just the raw votes, as under such methods, multiple elections in which the exact same votes are cast can have different numbers of wasted votes depending on the voters casting those votes.