Above all, they want your party votes. But how do those votes decide the makeup of Parliament? Photo / NZME
Under our MMP voting system, getting 35 per cent of the votes doesn’t mean you get 35 per cent of the seats. And just 46 per cent is probably enough to form a government. Here’s how it works.
Let’s imagine we’re voting for a Parliament of the Birds. The Kākāpō Party wins 37 per cent of the vote and the Tūī Party wins 34 per cent. The Kea Party gets 9 per cent and the Hoiho and Pīwakawaka parties get 5 per cent each, which is the minimum threshold for being represented in Parliament.
Several other parties – Seagulls and Shags and the like – get a total of 10 per cent, but none of them reaches 5 per cent on its own.
Parliament has 120 seats. Kākāpō will get 37 per cent of them, which is 44 seats. Tūī's 34 per cent will give it 41 seats, Kea gets 11 and Hoiho and Pīwakawaka get 6 seats each. Right?
Wrong. That’s only 108 seats. So who gets the remaining 12?
In this Parliament of the Birds, the 10 per cent of votes for Seagulls, Shags and others are effectively discarded. The missing 12 seats are then distributed to the parties that did get into Parliament.
The Electoral Commission does this in a slightly weird and wonderful way, using a formula invented 113 years ago by a French mathematician called André Sainte-Laguë.
Before explaining how it works, let’s back up briefly.
In a New Zealand general election, every voter gets two votes: one for a party and one for an electorate candidate.
It’s entirely your choice whether to cast them both for the same party, or vote differently for each, or cast only one of the two votes. Or not vote at all, for that matter.
The party votes determine how many MPs each party will have overall. The party, or group of parties, with at least half the MPs gets to form a government.
This is a “proportional” voting system: the proportion of all the votes each party gets determines the proportion of seats it is allocated in Parliament.
Electorate winners, on the other hand, are decided by a “first past the post” system. The candidate who wins more votes than any other becomes your local MP.
There are currently 72 electorates: 65 general seats and 7 Māori seats. The remaining 38 seats go to “list MPs”.
These list seats are allocated to each party to ensure proportionality, or relativity, is maintained. The total of both types of MP for each party reflects its share of the party vote.
Parties must announce their lists, in order, ahead of the election. In Parliament, both types of MP have completely equal standing.
Because of all this, the party vote is usually the most important. If your main purpose in voting is to help the Pīwakawaka Party, give them your party vote.
But if you’re in an electorate that Pīwakawaka is really trying to win, perhaps in order to be in Parliament, give them your electorate vote as well. This is true for all parties.
In broad terms, this explains the democratic makeup of Parliament. But the reality is a little more complicated.
To start with, anomalies arise because of that 5 per cent threshold and the exception granted to parties that don’t reach it but do win an electorate seat.
In the last election, for example, NZ First failed to return to Parliament: it gained 2.6 per cent of the vote and did not win an electorate.
But Te Pāti Māori, then called the Māori Party, gained only 1.2 per cent of the vote, yet it had two seats in Parliament. This is because it won the electorate of Waiariki. The threshold was set aside and the normal proportionality rules kicked in. That 1.2 per cent was just enough to give it a second MP.
So how does the Sainte-Laguë formula work? How do they assign the seats that weren’t filled because 10 per cent of the votes went to parties that didn’t make it into Parliament at all?
Using Sainte-Laguë, the commission counts up all the electorate winners and then starts to allocate the 38 list places. The first seat goes to the party with the biggest claim to it, on the basis that this will help preserve the overall relativity of the parties.
In our Parliament of the Birds, we know Kākāpō won 37 per cent of the party vote, but let’s say it won slightly fewer electorates. That means, to help restore the correct relativity, it will get the first list seat.
The next seat might also go to Kākāpō, for the same reason. The third might go to Tūī, the fourth to Kea, the fifth to Kākāpō again, the sixth to Tūī again, the seventh to Hoiho, the eighth to Pīwakaka, the ninth to Kākāpō, and so on.
By the time they get to 120, each party will have the number of seats that correspond proportionately to its share of the vote, relative to all the other parties’ shares of the vote.
In this parliament, Kākāpō would end up with 49 seats. Its 37 per cent of the vote turns into 41 per cent of the seats.
Tūī, with 34 per cent of the vote, would get 45 seats, which is almost 38 per cent of the total.
The boffins at the commission don’t sit in a room with an abacus, of course. Software does the calculations and it’s all publicly available on their website.
You can have a play yourself: you insert whatever potential results you’re interested in and the calculator tells you how many seats that would produce for each party. It’s great fun, if you’re that way inclined.
There’s also a cheat’s way to do it, which works like this. In our Parliament of the Birds, those 12 unallocated seats have to be shared among the successful parties.
So Kākāpō, with 37 per cent of the vote and 44 seats, also gets 37 per cent of the 12 seats. That’s 4.4, which (for the moment) gets rounded down to 4. For Kākāpō, 44+4=48.
Tūī's 34 per cent gave it 41, add another 4.1 and round it down for a total of 45.
Kea’s 9 per cent gives it 11+1.1 for a total of 12. For Hoiho and Pīwakawaka, 5 per cent of 12 is 0.6, just enough for another seat each: they both end up with 7.
But 48+45+12+7+7=119. Still one short. That last seat goes to Kākāpō, because under Sainte-Laguë the 4.4 it was rounded down from gives it a greater claim than the 4.1 and 1.1 of the other parties that were rounded down. Kākāpō's final tally is 49.
Remember, this is a cheat’s way and won’t be exactly right in all possible circumstances. But usually it will.
Who gets to be the government? In the Parliament of the Birds, if Kākāpō and Kea formed a coalition they would have 46 per cent of the vote.
Although this is less than half, their combined total of seats (49+12) would be 61. In a Parliament of 120 members, that’s half plus one: just enough to govern. The combined total of the others would be 59.
Kākāpō could also form a government if it had the support of Hoiho and Pīwakawaka. Their combined 47 per cent would give them 48+14=62 seats.
But Tūi could also form a government with this result. To do this it would have to persuade Kea as well as either Hoiho or Pīwakawaka to support it. Their combined 48 per cent of the vote would give them 64 MPs.
With all these options, a slight minority of total votes cast produces a majority of MPs. This is caused by the allocation of the seats “corresponding” to those discarded votes.
It’s not unfair to the opposition parties: whoever it is, their combined percentage of votes will still be less than the combined percentage of the government parties.
What if there’s an “overhang”? This occurs when a party wins more electorate seats than its party vote allows for.
Say there’s a Kōtuku Party that wins three electorates but only 1 per cent of the total party vote. The party vote says it should have 1 per cent of the seats, which is one seat. But it’s got three.
Kōtuku won’t have to give up two seats: all three winning candidates will become MPs. The system will simply add them to the total, so the Parliament has 122 MPs: an overhang of two.
When this happens it affects the overall percentages. Kākāpō, for example, would get 37 per cent of 122, plus 37 per cent of the 10 per cent of “discarded-vote” seats, which rounds up to 50 seats. One more than if the Parliament did not have an overhang.
Overhangs are quite common: they occurred after the elections in 2005, 2008, 2011 and 2014.
It’s easy to vote: choose the party you want and the candidate you want, and give them each a tick.
It can be complicated what happens next inside the workings of the Electoral Commission, but their online calculator does make it easy to follow.
As for the Parliament of the Birds, having all those Kākāpō, Tūī and Pīwakaka around might be kind of fun. Kea would do a bit of damage, though.
Simon Wilson is an award-winning senior writer covering politics, the climate crisis, transport, housing, urban design and social issues. He joined the Herald in 2018.
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