At-A-Glance: How IRV Works
- IRV is a simple to use system that elects the candidate most people most
want in a democratic fashion
- Voters rank candidates on their ballot according to preference
- If a candidate receives a majority of the first-choice votes, s/he is
elected, as in a normal election
- If no candidate has a majority, the lowest-scoring candidate is eliminated
and his votes redistributed according to his voters. second-choice candidates
- If a candidate now has a majority, s/he is elected. Otherwise, additional
instant "runoff rounds" take place until one candidate has over 50
percent of the votes, and is elected
- View an
interactive demo of IRV (this link will open a new window).
How Instant Runoff Voting Works
Voting with IRV is as easy as 1-2-3! All the voter needs to do is
rank the candidates. As San Francisco Reverend Arnold Townsend remarked, if you
can rank your three favorite ice cream flavors, you can vote using IRV.
The vote counting simulates a runoff election -- here's how it works:
Process
On the ballot, voters mark their 1st choice, 2nd choice and 3rd choice
candidates, and so on. Voters can rank as many or as few candidates as they want.
All ballots are then counted. If a candidate wins a majority
of 1st choices, he or she is elected, just like our present system. If
no candidate receives over 50 percent of 1st choices, the "instant
runoff" begins:
In each instant runoff round, the last-place candidate is eliminated, and
every voter's ballot is then recounted as a single vote towards the voter's
highest-ranked candidate still remaining.
IRV is very similar to the traditional two-round runoff system except that, by
knowing voters' next preferences in advance, a majority winner can be determined
"instantly," without requiring a second election.
The following examples help illustrate how IRV works:
Example 1
In this election, Alice received 60 percent
of the first choice votes, and is elected.
Because Alice received a majority outright, there was
no need for an instant runoff "round."
Example 2
In this election, Alice received 40 percent of
the first choice votes, to Bob's 35 percent and
Charles's 25 percent. Because no candidate received
a majority, an instant runoff round occurs.
Charles received the fewest votes, so he is eliminated.
His votes are redistributed to the candidate his voters indicated as their second choice.
5 percent of Charles's voters put Alice
as their second choice, compared with 20 percent who marked Bob
as their second choice. With Charles's redistributed votes,
Bob now has 55 percent - a majority - and is declared
the winner.
Resources
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