Undervote

An undervote occurs when the number of distinct choices selected by a voter in a contest is less than the maximum number allowed for a contest or when no selection is made for a particular election. Undervotes can be intentional or unintentional.

An undervote can be intentional for purposes including protest votes, tactical voting, or abstention. In a contested election, an undervote can be construed as active voter disaffection: a voter engaged enough to cast a vote without the willingness to give the vote to any candidate. Undervotes can also occur if a voter casting a ballot does not make choices in all available contests. An example is if, during a presidential election, a voter chooses a presidential candidate but does not select a candidate for a concurrently running election for county commissioner.

Alternately, undervotes can be unintentional and caused by many factors including poor ballot design. Undervotes caused by voting for a single candidate in multiple positions is usually caused by a voter's misunderstanding of the mechanics of the preference ballot.

Undervotes combined with overvotes (known as residual votes) can be an academic indicator in evaluating the accuracy of a voting system when recording voter intent.