Election Forecast updated

One News have released the latest Colmar Brunton poll, to be frank it’s a terrible result for Labour. Astonishingly, Andrew Little has even admitted that he has considered resigning as leader. Funnily enough, we’re now 54 days until the election, one day longer than Mike Moore served as Prime Minister.

Anyway, I’ve updated my election forecast and it holds an important lesson – don’t loose your marbles over one poll result. Despite Labour’s 24% result in today’s Colmar Brunton, they’re still holding at over 28% in the forecast. True, if the previous Roy Morgan poll was in fact a rogue, then the future results will be very different. We’ve got 54 days to wait and see.

Some good news for Labour

I’ve updated my polling forecast with yesterday’s Roy Morgan poll, which offers significant respite for Labour. The poll has Labour and the Greens combined on 44%, one point ahead of National who are on 43%.

This works well for Labour in my forecast. As the most recent poll it is weighted pretty heavily, keeping them very close to the 30% mark. They’d have 35 MPs and assuming no electorates changed hands then Priyanca Radhakrishnan, Jan Tanetti, Willow-Jean Prime, Kiri Allan and Willie Jackson would make it into Parliament off the list.

If Labour’s substantial field effort continues it’s not hard to see how they could chip another couple of percent off National – which could mean game over for Bill English. If you want to see a change of government in NZ: go out and knock on some doors.

I’ve also toyed with the possibility of including yesterday’s leaked UMR poll into my forecast. I’m keen to do so, it being a reliable poll, but the sticking point is the way they don’t have numbers for the minor parties. This means I need to change my code to ensure that they are not included as zero values thus bringing down the weighted averages for those parties. Watch this space.

Two big changes in the forecast

Okay, so I messed up.

Basically, I made some mistakes with the code behind my election forecast that adjusted for pollsters’ performance. Thanks to Nigel for the email pointing out my mistake.

So, today there are effectively two updates to the forecast. One is a fundimental change the model I’m using to predict the outcome of the election, and the other is a new data point, yesterday’s Colmar Brunton poll.

The overall result is Greens lose a huge amount of support, and National, Labour and NZ First all gain. To the point where NZ First would eclipse the Greens as the third largest party in Parliament.

On my new numbers the only new Green MPs would be Chloe Swarbrick and Golriz Ghahraman, while Denise Roche and David Clendon would lose their seats.

Marama Fox would lose her seat – the Māori Party would be reduced to a single MP.

Labour would be almost 17 points behind National, but that would be a decent improvement on their crushing defeat under David Cunliffe.

Their new list MPs would be Priyanca Radhakrishnan, Jan Tanetti, Willow-Jean Prime, Kiri Allan, Willie Jackson, Jo Luxton and Liz Craig. Their caucus would be 48.6% female – less than the required 50%.

Apologies for the change in my model, if anyone is interested I can rerun previous predictions with my new performance numbers.

Finally, some movement in the polling

I’ve updated my polling forecast with the latest data from the only NZ public poll released in April so far (seriously, we’re less than 150 days out from a general election and there has only been one poll this month).

We’re finally starting to see some movement in the forecast, although it is still fairly minor. While NZ First are moving up in their party vote, it’s not yet enough to net them another List MP.

The Greens however have just nudged high enough to grab another List MP, at the expense of National.

This won’t have a significant impact. To form Government on the numbers predicted before this poll was released, Bill English would have had to rely on support from NZ First, that does not change).

Can we just have some more polls, please?

Labour, Greens and Māori edge up

The latest One News Colmar Brunton poll has been released, I’ve updated my model accordingly.

The updated predicted outcome is exactly the same, in that each party would still get the same number of seats as they did before this poll was released. However, some movement has been observed.

Labour is now up 0.5 per centage points, so they must be very close to getting a 35th seat. Also, both the Greens and Māori Party are also observing an increasing trend in support with both of them increasing 0.4 percentage points and also being close to pickup an additonal seat.

I think this result shows the value in a model like this – significant new movement will still be observed, but will only end up showing in the results if it eventually forms part of a trend. In essence, we’re doing what we can to nullify “rogue polls”.

2017 Election Forecast released

There are few things that annoy me more than how blogs and Twitter light up after the release of a single political poll.

Pundits will make the huge inferences from statistically insignificant changes, or attribute meaning to an event that occurred after polling finished.

Today I’m proud to release something I’ve been working on for a while, a forecast model for the 2017 New Zealand General Election. It is a mathematical model for analysing polling and determining what Parliament would look like if an election were held today.

Check it out here or via the permalink at the menu on the top of this page.

It takes all available public polling, adjusts for historical data (for instance, known bias’ that individual pollsters have), produces a weighted average based on recency and sample size.

It then produces an estimate of each party’s seat count in the Parliament.

No doubt people will have a ton of questions, hopefully the following will answer them. If you have any further questions, or ideas or suggestions, please either leave them on here, or email me directly on patrick.leyland@gmail.com

Lastly, my thanks to the many people on both sides of the Tasman (you know who you are) who have helped me with the coding, maths, and design. Hopefully you’ll find it useful!

Details

Continue reading “2017 Election Forecast released”

The Māori seats

One of the pecularities of MMP is that because of the proportional representation provided by the party vote, there is virtually no electoral benefit to winning electorate seats (there are other political benefits, which I’ve touched on previously). So even though it looks like a few seats like Napier and Christchurch Central might come down to the wire, the outcome isn’t going to change who forms government.

The one exception to that is of course parties that use the “coat-tailing” rule – that is, they get less than 5% of the party vote but still get an electorate MP and possibly some list MPs due to winning an electorate seat.

Given the survival of the Māori and Internet Mana parties both rely on winning a Māori electorate seat (as they are both polling consistently below 5%), these seven seats can actually have a very important impact on the makeup of Parliament.

One of the other unique things about the Maori seats is that they are the only electorate seats that regularly get polled. Māori TV have commissioned a series of polls from Reid Research (and TVNZ’s Marae used to also poll). I’ve compiled this years poll results, plus the results from the 2011 election and the 2011 poll results (where I can find them – if anyone has any of the missing numbers please send them through!).

It’s worth taking these results with a grain of salt – the sample sizes are very small (normally 400) and that, combined with poor turnout in the Māori seats make for lots of inaccuracies.

That said, today’s Te Tai Tokerau poll is the tightest yet – with Hone Harawira polling only one point ahead of Labour’s Kelvin Davis. If Kelvin manages to win the seat (and a good turnout operation could certainly help close that gap), then the Hone Harawira/Kim Dotcom farce is over.

Interesting times indeed.

Note: All numbers are candidate, not party vote.

Electorate Candidate 2011 poll 2011 result 2014 poll
Te Tai Tokerau Labour 35 35 37
Māori Party 20 16 9
Mana 42 41 38
Greens
Tāmaki Makaurau Labour 23 35 27
Māori Party 58 40 28
Mana 14 16 14
Greens 3 8 7
Waiariki Labour 22 25 17
Māori Party 56 43 50
Mana 22 32 21
Greens 2
Hauraki-Waikato Labour ? 54 57
Māori Party ? 16 14
Mana ? 21 10.4
Greens
Ikaroa Rāwhiti Labour ? 41 37
Māori Party ? 20 18
Mana ? 26 21
Greens ? 11 6
Te Tai Hauāuru Labour ? 30 29
Māori Party ? 48 32
Mana ? 9 10
Greens ? 11 11
Te Tai Tonga Labour 35 41 48
Māori Party 46 32 17
Mana 9 8 9
Greens 10 15 9