Derek Connery explains the complicated single transferable vote system that sees the electorate rank those standing by numerical preference

This election will see the single transferable vote (STV, not the TV channel) system being used again as it has been in Scotland for all local council elections since 2007.

Now the $64,000 question: how does it work? I thought I knew roughly but, in truth, I was clueless. It is quite a complicated system all told but it is thought to be fairer than the traditional first past the post (FPTP) methods and ensures that no vote is wasted.

This seems great in theory, but surely if you use a system that people struggle to understand then there is a problem and a lack of comprehension of the methodology is counter-productive to what you are trying to achieve in the first place.

So I am going to try to add some clarity to the proceedings.

The first rule of STV is the cross is out the window – we’re using numbers. Let’s imagine that a ward will have four members and on polling day eight candidates are standing. You would begin with a number one for your preferred candidate, two for your second choice and so on.

Okay, stop! You are not required to rank all the candidates. In fact, if you choose just only one, that is fine.

However, if you rank all of them you potentially ‘assist’ a candidate that you wouldn’t vote for in a month of Sundays.

Right, so now everyone has voted, the polls are closed and we are ready to start the count.

In this case, let’s say that 1,000 votes have been cast. Ah, but before the counting starts the returning officer has some homework to do. They have to work the ‘quota’. This is the number of votes required to win the seat. In FPTP, this was easy as it was who got the most votes. Duh! In STV, the quota (sometimes referred to as the droop quota) is worked out as follows.

Valid votes cast/ (number of seats available+1)+1 = quota. So for our example 1,000/ (4+1)+1 = 201. This means that any candidate who achieves 201 votes or more is duly elected. So the next job is to count the ballot papers and see how many first choice votes each candidate got, for example

Candidate 1 = 100; Candidate 2 = 50; Candidate 3 = 150; Candidate 4 = 250; Candidate 5 = 30; Candidate 6 = 199; Candidate7 = 201; Candidate 8 = 20. This means that candidates four and seven are duly elected. So as the quota is 201, none of number seven’s votes are re-allocated. However, 49 of number four’s votes have to be redistributed.

This is done by now looking at second preference on all the papers that had number four as first choice and excluding number seven as they are already elected. Candidate 1 = 20; Candidate 2 = 30; Candidate 3 = 150; Candidate 5 = 20; Candidate 6 = 25; Candidate 8 = 25.

Now the next step: clearly number four is only transferring 49 votes and not the whole 250. Therefore it is necessary to work out how many actual votes based on the ratio of 49 to 250 approximately 0.2. This translates to the following ‘transfer’ of votes. Candidate 1= 20 * 0.2 = 4 so this means four votes pass to candidate one giving them a new total of 104, following this through for the others means the new count is as follows: Candidate 1 = 104; Candidate 2 = 65; Candidate 3 = 180; Candidate 5 = 34; Candidate 6 = 204; Candidate 8 = 25

So now candidate six is elected, and at this stage candidate eight is excluded as they have the least number of votes and the redistribution of their votes begins. This process continues until the right number of candidates is elected or the returning officer loses the will to live, whichever comes first. The Electoral Commission has a much easier explanation and it is, as said at the beginning, not necessary to rank every candidate. Only rank those who you would be happy to see your vote transferred to.