In some cases, they reflect voter disaffection, where an individual participates in the election but declines to support any candidate in a specific contest.
[2] For example, a voter might select a presidential candidate but abstain from voting in a concurrent county commissioner election.
For instance, a voter mistakenly marking a preference ballot by selecting the same candidate for multiple positions could lead to an undervote.
[4][2] Undervotes, together with overvotes (where a voter selects more options than allowed), are collectively referred to as residual votes.
These are used in academic studies to assess the accuracy and reliability of voting systems in capturing voter intent.