The Supplementary Vote System

As mentioned of the voting systems being proposed I found the Supplementary Vote system to be the simplest that still allows for a majority win. In that entry I kept the mechanics and the politics vague, now it's time to look a little deeper.


From the point of view of the voter little will change. The candidates names will still be listed on the left-hand side of the paper, but running down the right will be two rather than just the one column. Heading the first column will probably be "Primary" and "Secondary" across the next. Above that will be something along the lines of "Mark ONE cross in the Primary column for your preferred candidate and ONE cross in the Secondary column for your alternative candidate".

All votes in they're taken away and all Primary votes are tallied. If no candidate achieves over the 50% mark the secondary votes are tallied and added, the winner is the candidate with the most votes.

So let's run it with a simple three candidate election using Alphans, Betans and Gammans. The vote is in and the primary results are a 40/35/25 split; no candidate has the required 50% so the secondary votes are tallied.

Now the Alphans hate the Betans and vice-versa and the Gammans aren't fond of the Alphans. So every Alphan and Betan secondary vote goes to the Gammans and every Gamman secondary vote goes to the Betans. Yeah so that's

Alphans 40 - Gammans 40
Betans 35 - Gammans 35
Gammans 25 - Betans 25

So the split becomes 20/30/50. In the First Past the Post System the Alphans would have won with 40% of the vote, in this system they now come last with the previous 'losers' the Gammans taking the seat.

Of course that's assuming a full and correct vote. What happens if I vote for the Alphan with my Primary vote and my Secondary vote?

Alphans 40 - Alphans 40
Betans 35 - Gammans 35
Gammans 25 - Betans 25

The split is 40/30/30 and the Alphans win despite the fact only the same people voted for them each time. So either a ballot that has both votes for the same candidate is listed as spoilt, or only the Primary vote counts. To keep intention clear I'd opt for the later.

[Update as Tav has pointed out in the comments only the top two are kept, however we've both got it wrong in that only the secondary votes of the dismissed candidates are counted. Thus Alphans and Betans are kept. Secondary votes of the Gammans are tallied and the result is 40/60. Betans are elected.]

What if a voter gets confused and only puts one cross on the ballot and that was in the Secondary column?
The fact that haven't voted for a Primary candidate makes intention clear, the Secondary vote becomes a Primary vote with no Secondary.

How will this alter the face of politics. Let's add a couple more parties the Deltans and the Etans. The Deltans lean towards the Betan line whereas the Etans have Alphan tendencies. So normally the vote could get split between these four parties. For a primary vote imagine 5% of the larger parties votes are siphoned off to the smaller party in each vote.

Alphans 35
Betans 30
Gammans 25
Deltans 5
Etans 5

Now add the secondary vote along the same principles as before.

Alphans 35. Gammans 30, Etans 5
Betans 30. Gammans 25, Deltans 5
Gammans 25. Betans 20, Deltans 5
Deltans 5. Betans 5
Etans 5. Alphans 5

So the split becomes 20/27.5/40/7.5/5 with the Gammans once again as the winners though this time without the 50% majority.

[As before with only the top two candidates kept and counts from the others. Thus again Alphans and Betans are kept and the results are 40/55 (5 to Deltans from Gammans not counted) and the Betans win.]

Of course this is all nice and clean and, but hopefully it shows the reduction in tactical voting and the splitting of the vote. There's no need for a Gamman to vote Betan to keep the Alphan out, nor do the Alphans have to worry so much about the Etans splintering their vote and allowing the Betan in.

Head over to the Electoral Reform page for additional information. I don't necessarily think all of their points merit attention, but I would be amiss not to draw them to the reader's attention.