How are ballots counted with proportional ranked choice voting (also known as PR-STV)? Watch these 4 videos:
How the Ballots are Counted: The Simplest Way
PR-STV is a proportional system where voters elect a team of
local MPs using a ranked ballot.
How the votes are usually counted with proportional ranked
To get elected to one of the seats in the local riding, a candidate
would need a certain number of votes. This number is called a
The quota (how many votes needed to win a seat) will depend
on how many voters there are, and how many seats there are.
You can figure out the quota for your riding by taking the total
number of ballots cast, divided by the number of MPs to be
elected plus one, plus an additional one.
So, if there are 100 voters and 4 candidates to be elected, each
MP would need 21 votes. (100 / 4+1) + 1 = 21). Watch
the videos above and try PR-STV here.
Bottom line: all you really need to know:
In a five seat riding, a candidate would need about 16% of
first-choice votes to be elected. In some cases the last MP to fill
a seat will be elected with less than a full quota (as low as 10%).
In a riding that elects more MPs, that threshold would be lower.
In a riding with fewer MPs, that threshold would be higher.
Part Two Below:
From the perspective of the voter, STV is straightforward. Voters mark their first choice candidate with the number 1, and then continue to rank other candidates in order of choice (2, 3, 4...).
These preferences are transferred from one candidate to another as
the ballots are counted.
While each voter has one vote, by indicating a ranking of candidates, the voter is
in effect instructing the returning officer what to
do with that vote.
While voters have the option of ranking all candidates on the ballot paper, in practice the average number of preferences indicated is about four.
- from "The 2011 Irish General
Election" by the UK Electoral Reform Society
Credit for diagram below goes to the
Library of Parliament Research publications