The New Zealand Voting System
One of the more curious of the electoral systems I am likely to cover for some time, the NZ parliament is elected using a mixed-member proportional representation system to elect its lower house. (Although NZ used to have an upper house, they pulled a Queensland in 1950 and abolished it.)There are 71 electorates in New Zealand, which are elected by first-past-the-post systems, so whoever gets the most votes wins each of these seats. However, there are 120 seats in the parliament, sometimes more. This is because New Zealand voters also get to vote in a proportional representation system. This may be best illustrated by a 2-party example:
Party A wins 31 seats, and 40% of the proportional vote. Party B wins the remaining 40 seats and 60% of the proportional vote. Using a simple allocation of the seats (rather than the more complex Sainte Lague method they actually use that favours minor parties) Party A is entitled to 40%*120 = 48 seats, so adds 17 more members from its party list, and Party B is entitled to 60%*120 = 72 seats so adds 32.
This means that for predictive purposes the electorate votes are largely irrelevant; and miscalculation will generally be covered by the additional proportional vote. In other words, predict the proportional vote, and you predict the government.
The Popular Vote
In order to win any seats, a party must either gain 5% or the proportional vote or win a seat outright. Looking at the polls taken throughout the month of September, only four parties were expected to exceed 5% at any point: the ruling National Party, the opposition Labour Party, the Labour-alligned Greens Party and the free-floating NZ first:| Poll concluded: | National | Labour | Green | NZ First |
| 20 Sep | 45.8% | 37.3% | 7.1% | 7.1% |
| 19 Sep | 46% | 37% | 8% | 5% |
| 13 Sep | 40% | 44% | 7% | 6% |
| 11 Sep | 47.3% | 37.8% | 4.9% | 6.0% |
| 10 Sep | 40% | 39.5% | 9% | 6% |
| 6 Sep (Newsroom) | 30% | 45% | 6% | 11% |
| 6 Sep (One News) | 39% | 43% | 5% | 9% |
| 5 Sep | 38.9% | 41.1% | 6.7% | 8.9% |
Importantly, given the left-leaning nature of the Green vote, the latest polls are very close for a Labour-Greens coalition:
| Poll concluded: | National | Coalition |
| 20 Sep | 45.8% | 44.4% |
| 19 Sep | 46% | 45.0% |
| 13 Sep | 40% | 51.0% |
| 11 Sep | 47.3% | 42.7% |
| 10 Sep | 40% | 48.5% |
| 6 Sep (Newsroom) | 30% | 51.0% |
| 6 Sep (One News) | 39% | 48.0% |
| 5 Sep | 38.9% | 47.8% |
Nevertheless, on the most recent data it would look like a narrow National lead, depending on the NZ First to play king/queen-maker. However, we've seen a lot of inaccurate, narrow polling in the last 18 months: Brexit, US Presidential and UK National. The French Presidential election--by contrast--was reasonably well predicted but far from close.
The first two of these surprise results favoured the right, the third favoured the left, so this is not necessarily a phenomena measured well on the traditional left-right spectrum. All three, however, supported the underdog and all three swung further than expected in favour of change. To say all three favoured the "unpopular" choice would be misleading, since in Brexit the "unpopular" vote won first-past-the-post (and in the US Trump also won, though not on the popular vote); it may be accurate to suggest, however, that these hidden votes supported the politically-incorrect/media-ridiculed position. Although polling is anonymous it would seem that people with these 'socially unacceptable' positions (for lack of a better word) are still hesitant to disclose these positions to polsters.
What does this mean in NZ? Support for the underdog would play into Labour's hands--especially considering that two months ago before a leader change their polling was about 20 percentage points lower. Support for change would also support Labour. However the rise of Jacinda Ardern, the new Labour Leader, has made her something of a media-darling. As a result there is less motivation for a 'hidden' vote.
Is the appetite for change fully represented in the polling above? There will be no way to tell until tonight. But it should not be as dramatic as the Brexit vote (probably in the area of around 10 percentage points).
My predictions, therefore, are:
1) a Labour-Green combined result outperforming the Nationals, but probably with Labour taking ground from Greens.
2) the Labour-Green combined result being sufficient to form government, but
3) NZ First will refuse to cooperate with the Greens IF they end up holding the balance of power; unless Labour can form a >50% coalition with NZ First, they will see NZ First crown the Nationals to public outcry.
