An undervote occurs when the number of choices selected by a voter in a contest is less than
the maximum number allowed for that contest or when no selection is made for a single
choice contest.

An undervote can be intentional for purposes including protest vote

Protest vote

A protest vote is a vote cast in an election to demonstrate the caster's unhappiness with the choice of candidates or refusal of the current political system...

s, tactical voting

Tactical voting

In voting systems, tactical voting occurs, in elections with more than two viable candidates, when a voter supports a candidate other than his or her sincere preference in order to prevent an undesirable outcome.It has been shown by the Gibbard-Satterthwaite theorem that any voting method which is...

 or abstention

Abstention

Abstention is a term in election procedure for when a participant in a vote either does not go to vote or, in parliamentary procedure, is present during the vote, but does not cast a ballot. Abstention must be contrasted with "blank vote", in which a voter casts a ballot willfully made invalid by...

. Alternately undervotes can be unintentional and caused by many factors including poor ballot design.

Undervotes combined with overvote

Overvote

An overvote occurs when one votes for more than the maximum number of selections allowed in a contest. The result is a spoilt vote which is not included in the final tally....

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

External links

• Champaign County Illinois November 2006 Undervote Analysis