Is Preferential Voting indeed Preferable?

Australia is a unique country. It is the only country to use instant run-off voting (IRV), better known as preferential voting. The nation is split into 151 single-member electorates where the voters choose who they want as candidate by labelling every candidate in descending order of choice. If no candidate receives a majority, candidates with less votes are eliminated and their preferences redistributed until a candidate receives a majority.

Many other countries such as the United Kingdom and the United States use First Past the Post (FPTP) instead. In this system, the candidate with the most votes wins the seat, regardless of if they have a majority or not. Under this system, Boris Johnson won a “stonking” majority with only 43.6% of the vote. It raises the question – how differently would our elections have gone under this older system?

Fortunately, it is very easy to translate an IRV result into a FPTP result if you have the raw data. This data was sourced from the Australian Electoral Commission Tallyroom and it has all the voting data per candidate for every polling booth in the nation. From there, it is a matter of spreading the data so every party is a column, aggregating by polling booth and finally tallying up which party wins each seat.

However, a few assumptions are needed:

  •  There is no tactical voting, i.e. people do not change their vote to a candidate with a better chance of winning.
  • The results of a previous election do not affect the next. e.g. Abbott winning 2010 would not change how many votes he gets in 2013.
  • There is only one independent per electorate and they get all the “independent” votes.

Below is the table of the seats won. For all elections aside from 2019, there were 150 seats up for grabs. In 2019 there were 151 seats instead. Keep in mind that we are looking at each election individually and not a continuous cycle of connected elections.

Parties 2019 2016 2013 2010 2007
Liberal 67 78 66 77 81 95 66 75 55 67
National 10 11 10 11 9 10 6 6 10 5
Labor 68 58 69 57 55 43 72 66 83 76
Green 1 1 1 2 1 1 1 0 0 0
Katter 1 1 1 1 1 0
Ind./OTH 3 2 3 2 3 1 5 3 2 2

Screen Shot 2020-02-28 at 7.17.03 pm

If we followed FPTP and no adjustments were made to voting habits, the Morrison Miracle would instead become a Morrison Massacre with the coalition winning 89/151 seats. Turnbull’s Tumble that almost lost the majority under preferential would have fallen 1 seat short of Morrison with 88/150 seats. The Liberal Party still would have lost 2007 but Labor’s seats would fall from 83 to 76 out of 150, a narrow majority. Tony Abbott would have convincingly defeated Gillard in 2010 and his landslide in 2013 would have moved up from an amazing 90 seats to an awe-inspiring 105 or 70% of parliament!


So why is this so different? It all comes down to vote splitting. In Australia, there is only one viable right-wing party – the Liberals, their National allies or their counterparts in another state. However, Labor and the Greens both enjoy a degree of support from the left. While the Greens seldom win seats, they often rank a respectable third. Under our preferential system, this is no problem for Labor. If the Green candidate fails to win the seat, chances are their second preference will go to Labor. Under FPTP however, this does not happen and so the left vote is split.

While Australia is set on preferential voting and indeed it is more fair, I am sure we can all admire the beauty of such a blue parliament.








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