There are several methods of voting which allow voters to rank
candidates in order of their preference, rather than just selecting a
single desired candidate and then doing a single count (Plurality or
"First Past the Post" voting). The system specifically used in
Australian elections is "Instant-Runoff Voting" (IRV).
IRV is intended to allow for a variety of political parties of various
sizes to flourish (unlike the famously two-party-dominated politics of
the USA) as citizens who vote for a minor party as their first
preference don't "waste" their vote; if their first preference is too
obscure to get in, their vote goes to their second preference, and so on.
However, it is still possible for "vote-splitting" to have a negative
effect on minor parties - in some cases, giving a candidate a higher
preference can paradoxically cause them to lose, as they can be
eliminated earlier.
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