Clone (voting)

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In the analysis of voting systems, a clone is an additional candidate who is equal in attractiveness to each voter with an existing candidate. In preference voting systems, voters will rank apparently identical candidates next to each other. In some systems, the introduction of a clone will tend to divide support between the similar candidates, making it less likely either will be elected. In some other systems, the presence of a clone will tend to reduce support for dissimilar candidates, making it more likely that one (or more) of the similar candidates will be elected. In yet other systems, the introduction of clones will not significantly affect the chances that one of the similar candidates will be elected. There are further systems where the effect of the introduction of clones depends on the distribution of other votes.

Examples of the effects of clones

Clones harm similar candidates

• Plurality voting system

Clones help similar candidates

• Borda count

Clones can help or harm similar candidates

• Bucklin voting

Clones have no impact

• Instant-runoff voting
• Approval voting
• Range voting
• Schulze method