Preferential Voting, specifically the Irish voting system.


So the Irish local and EU elections are currently counting, could someone explain to me specifically how the process when a candidate exceeds their wrote works? Like how the votes are distributed amongst the other candidates. Examples are welcome!

In: Other

In preferential voting you score candidates in order of preference, 1, 2, 3 etc.

They count all the votes marked 1. If they get enough votes to win, then they win. If they don’t get enough votes to win then they eliminate the candidate in last place and count the votes marked 2 on those ballots. Repeat for the other numbers until someone wins.

So you have candidates Tom, Dick and Harry. Tom gets 5 votes marked 1, Dick gets 3 and Harry gets 2.

Harry is eliminated. Those two votes for him are now transferred to someone else. They look at who they voted 2 for. Tom gets one, Dick gets one.

Tom now has 6 votes, Dick has 4. Tom has a majority and wins.

The EU vote is a bit different. Say an area has 10 seats up for vote. The TDH Party put up three candidates, Tom, Dick and Harry. If they win one seat, Tom becomes an MEP. If they win two seats, Harry also becomes an MEP.

The EU election is a little more complicated than that. Once a party has won a seat, the number of their votes is divided in half and the next seat goes to the next highest scoring party (which might still be them). So if the TDK get 6 or the 10 votes, they win a seat. Then their score is counted as 3 to see if they win the next seat. If they win that second seat then their score is divided by 3 instead so their score counts as 2 to see if they win a third seat for poor Harry.

As I understand it (and I’m sure I’ll be promptly corrected if I’m wrong) you rank the candidates in order of preference. Everybody’s primary choice is counted, and if nobody has secured 50%+1 votes, the candidate getting the least votes is eliminated. Anybody who selected that candidate as their top choice is now switched to their second choice candidate. If there’s still no 50%+1 winner, they drop the new lowest vote getter and replace those votes with the next candidate on those individual’s ballots. Repeat until one Candidate has achieved 50%+1 or more of the total votes, and that person wins the election.

So there’s a quota for how many votes someone needs to get to be elected, generally some percentage of the overall vote, like 25% plus one vote for a three-seat vote.

Let’s say we have a 1000 voter constituency with a three-seat vote, and Candidate A has obtained 300 votes. Since 251 votes is what’s necessary to be elected, there’s a surplus of 49 votes. 30% of Candidate A’s voters had Candidate B as their #2, while 70% of Candidate A’s voters had Candidate C, and 0% had Candidate D. The votes are split up amongst the candidates like this:

34 to Candidate B (70% of 49 is 34.3)
15 to Candidate C (30% of 49 is 14.7)

This is a simplified version of the process – if you want to read in depth about how votes are split (especially when there are multiple candidates who have exceeded the threshold), check out this article:

There are many preferential voting systems. They all require the voters to rank their choices instead of choosing just one of them. This is used in Ireland for their “single transferable vote” system which have gained a lot of popularity in the world as an alternative to the classical voting systems. Say for example that you would preferably that a small extreme party would win. However you know that just a tiny group of people would agree with you. In a classical voting system your vote would have been better used voting for a popular moderate candidate as this would prevent the “other” side of the political spectrum to gather enough votes for their most popular candidate. However in Ireland with their STV system you can rank your preferred candidate highest. If it turns out that that candidate is not going to win then your vote automatically switches to your second preference, which might be a more popular extreme candidate. After a few more rounds of candidates being eliminated this candidate might also get eliminated and your vote is then for your third preference. This goes on until you have one candidate that gets most of the votes.

CPC Grey does a great job explaining this in an easy to understand way: