A petition calling for a referendum on Whanganui's voting system was put before council by Steve Baron in September 2017. At the time councillors decided to include the poll in this year's local body elections, rather than hold a separate poll.
"It comes down to simple fairness and mathematics," Baron said.
"Our mayor was elected [in 2016] with 39 per cent of the vote and simple mathematics tell you that 61 per cent of voters didn't actually want him as mayor."
Baron said STV is more important for selecting a mayor, but that it could also have a small effect on voting for councillors.
Mayor Hamish McDouall said it's appropriate to give the choice to the public.
"I think how we elect our representatives is a key issue and I don't think it should be left up to elected members, otherwise you may have people voting in a self-preservatory way."
In 2017 the council ran a survey which 187 people responded to. The survey showed 63 per cent preferred FPP and 37 per cent preferred STV.
McDouall said he thinks this year's poll result could be much closer.
"It's very hard to displace an existing system, but we in New Zealand have done that before with MMP replacing FPP for our general elections, and also we all vote STV for the District Health Board," McDouall said.
"There's no mayoral election this year so, rather than picking a mayor, people should put their efforts into what voting system they want."
University of Otago politics professor Janine Hayward said FPP produces incredibly disproportionate results while STV is a proportional representation electoral system, and does a better job at translating votes into who is elected.
"The two different systems act in completely different ways, so depending on which one is used there can potentially be very different outcomes in the election," she said.
"When we vote using FPP people are able to cast multiple votes so one voter can over represent themselves to the detriment of other voters.
"It kind of makes sense that a voting system like STV, which is a single vote, means immediately I can have less influence over who is getting elected because I'm just electing one person to represent me, which seems reasonable."
Hayward said voter participation can be affected by which voting system is in place.
"STV has the potential to encourage voter turnout because of the ways it can reduce incumbency and promote change in council, and we know FPP tends to drive down voter turnout in countries that are using it.
"[With STV] a much larger number of people can see in the council that's elected that their vote matters and they can point to someone in that council that they helped to elect."
Voters will also be asked if Whanganui should introduce voting wards, and if the number of Whanganui councillors should be dropped from 12 to 10.
The ward system splits candidates into geographical areas or groups of people.
Whanganui District Council uses an "at large" method where councillors don't formally represent areas or groups.
The poll is non-binding which means the public will need to be consulted if any changes are considered by council.
The poll regarding the number of councillors is also non-binding.
Voting packs have been sent out and voting closes on October 12 at midday.
How FPP and STV work
FPP is a tick, and you have as many votes as there are vacancies:
In an FPP system you tick the candidates you want to represent you - with a total number of ticks allowed for the total number of vacancies.
So if you are a Whanganui District Council voter, you can only give your tick to a maximum of 12 candidates. The 12 candidates with the most votes will be elected. There is no election for the mayoralty as current Mayor Hamish McDouall was unopposed.
If you were to tick more candidates than you are allowed to, your vote would be invalid as it will be impossible for the electoral officer to work out which candidates you preferred.
STV ranks candidates and isn't limited by the number of vacancies:
Under the STV system you order your candidates by preference.
You are not limited to the number of vacancies - you can rank them all if you want.
You can rank just one by putting a number 1 by your choice, or you can rank them going down, so giving one candidate a number 1, then another a number 2 and so on.
You can rank more candidates than there are vacancies, but your numbers must follow an unbroken sequence.
So if you ranked candidates with number 1, 2, 3, 4 all your votes would be valid.
However, if you ranked candidates with number 1, 2 and 4, having left out a number 3, then your votes would only be valid for 1 and 2. After that, the electoral officer would not be able to determine your preferences.
To get elected, candidates need to reach a quota of the votes.
What is meant by "quota" in the Single Transferable Vote system?
The Department of Internal Affairs defines it as the number of votes needed to get elected.
In the case of single vacancy elections, such as a mayoralty, the quota is referred to as an absolute majority.
The quota is calculated by the STV computer software, based on the total number of votes and the number of vacant positions. The process treats all candidates the same by giving them a "keep value".
This "keep value" in the election results will show which candidate did best.
Here is an example:
If the "quota" (or number of votes needed to be elected) is 100 and the candidate gets only 100 votes, they keep all those 100 votes. So they have a keep value of 1 (100 per cent).
But if a candidate receives 200 votes, that person still needs only 100 votes to be elected. The others can be distributed to other candidates.
In this case the candidate's "keep value" would be 0.5 (50 per cent), because they only need 50 per cent of their votes to be elected.
In other words, the most popular candidates in an STV election will have the lowest "keep value".
How are the votes distributed to other candidates if my number one candidate has enough votes?
Through the ranking system.
If your "number one" candidate has more than enough votes, your vote would then be transferred to your number two candidate.
If they also have enough votes, then it would be transferred to your number three, and so on.
What if no candidate reaches the quota?
If no candidate reaches the quota then the lowest polling candidate will be eliminated. Their votes will then be transferred to their voters' next preferences.
So, under STV should I rank every candidate or just the ones I want to be elected?
There is no rule on this. You can rank every candidate, or you can just rank some.
The more candidates you rank, the more you are helping - which is good if you want to help them but not if you don't.
Giving a ranking, even a low one, to a candidate, means potentially giving part of your vote to them, and it could help them. So if you really don't want a candidate, then don't rank them at all.
Voting progress
So far 3350 voting papers have been returned to the electoral officer for the Whanganui District Council election.
It's a much lower return than at the same stage in the 2016 election when about 6000 papers had been returned a week after voting opened.
