Election season is upon us once more, and that can only mean one thing: that’s right, a voting system to familiarise yourself with. All elections for positions in the Student Association will use single transferable vote (STV), which has many advantages over other voting systems but is harder to explain. 

If you haven’t voted in the Student Association elections before, or even if you’ve been confused about the voting system in the past, then worry not - while STV isn’t as straightforward as many voting systems you’ll have used before, we can explain it simply here.

In many countries, including the United Kingdom, the United States, and India, we use a system called first-past-the-post. Everyone votes for one candidate, and whoever has the most votes at the end wins. This system is simple, but it has one huge disadvantage: it doesn’t guarantee that the overall winner has the support of a majority of voters.

Let’s take an example. Say we have three candidates for Director of Events and Services (DoES): Amy, Ben, and Cathy. The main issue that they’re arguing over is the quantity of ABBA to play in the Union. The student population of St Andrews, in its infinite wisdom, is broadly in favour of ABBA: 65% of them believe that the only way they can truly enjoy their night is with Super Trouper playing as they hit the dance floor. However, there remains a contingent that despises them: 35% would be happy never to hear Anni-Frid as long as they live.

Amy and Ben have both taken strong pro-ABBA stances, while Cathy never wants to hear Dancing Queen in 601 ever again. However, Amy and Ben disagree on exactly how much ABBA should be played; Amy doesn’t think that any other band is worth playing, while Ben would at least like a few other 80s hits interspersed among them.

Voting day comes, and it plays out as follows:

Cathy becomes the DoES and instantly makes it an offence to even so much as mutter “Björn Ulvaeus” in the union. But this isn’t what the vast majority of students wanted. What went so wrong?

What happened is known as the spoiler effect - when two candidates with similar views split the vote between them and allow a third-party candidate, who may have a completely contrary stance on these issues, to win the election. There are several notable real-world examples of this - somewhat infamously, in the 2000 U.S. Presidential Election, George W. Bush won the state of Florida (and, consequently, the overall election) by a margin of just a few hundred votes over Al Gore. The Green Party candidate, Ralph Nadar, took almost 100,000 votes in the state - almost five hundred times Bush’s margin of victory. As the differences in policies between Gore and Nadar paled in comparison to the differences between either of them and Bush, Nadar was widely blamed by Gore supporters for “spoiling” the election and letting a candidate that neither of them wanted to win.

STV allows us to (mostly) avoid the spoiler effect. Although no voting system will have every feature we desire (see Arrow’s Impossibility Theorem if you’re really interested as to why), it does a pretty good job of ensuring that whoever wins has the support of a majority of students. .

There are two settings that STV can be used in: electing a single candidate and electing multiple candidates. In the Student Association elections, only the first of these methods (more properly called instant runoff voting (IRV)). But first, let’s go over how to cast your vote!

STV: Voting

Voting using STV is very easy, provided you are able to count. Simply rank the candidates available in order of preference. For instance:

ELECTION FOR DIRECTOR OF EVENTS AND SERVICES (DoES)

Please rank your candidates in order of preference, putting a ‘1’ next to the name of your first choice, a ‘2’ next to your second choice, and so on.

Three very important notes here:

• Only use each number once! You can’t make two candidates your first preference.

• You don’t need to number every candidate! You may want to, but if you have no strong preferences between the last few candidates, it may be best to leave it (see Donkey voting as for why).

• RON isn’t a candidate! It stands for ‘Re-open nominations’; if you’re dissatisfied with all the candidates in the race, you can vote for this option. If it wins, then the election will be held again with the potential to have new candidates.

STV: Electing a Single Candidate

Now that the votes have been cast, what happens? Counting them in a single-member race is fairly easy. Amy, Ben, and Cathy are continuing to bicker over ABBA, while three more candidates, Drew, Eilidh, and Felicia, are focusing on more niche artists, such as Tame Impala and The Beatles. Let’s say that this happens (we’ll ignore RON for simplicity):

Amy leads in the first round of voting, but she hasn’t won yet. When a single candidate is being elected, then they must win over 50% of the vote. As you may have guessed from the name, the votes are transferable - they can pass from one candidate to another. Under STV, the candidate with the lowest number of votes is eliminated, and their votes are transferred to the next-preference candidate who has not yet been eliminated. If the voter hasn’t written any more preferences down, then the vote is (sadly) discarded.

In this scenario, Felicia has the lowest number of first preference votes, so her 69 votes are redistributed among the other candidates.

Felicia and her voter base (who are still hooked on early 2010s emo bands) don’t care too much for most other music, but they can get behind Lay All Your Love On Me playing on repeat, so most of them decide to vote for Ben. However, voters are autonomous, and don’t necessarily follow any patterns, so most candidates gain a few votes.

Eilidh is next to be knocked out, and her votes also mostly transfer to Ben. Note that Ben has hugely increased his number of votes here, revealing another benefit of STV:  making sure that you can appeal to a wide variety of people and not just a small following is crucial for winning under STV.

Ben has narrowly beaten Drew, and they are promptly eliminated from the contest. Drew’s voters are agnostic on ABBA, so they’d hate to have Amy win. They are, however, willing to accept Ben’s compromise.

Amy’s extremist views on ABBA have proven fatal for her campaign, with Ben overtaking her in the fourth round. However, Amy’s supporters still have a vote, and would far rather that Ben won than have ABBA banned outright.

After the last transfers are complete, Ben takes over 50% of the vote, and is hence declared the winner of the election. All in all, even if it’s a more complicated system than FPTP, it’s vastly fairer and delivers results that more people are happy with.