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Archive for June, 2011

[Update: Election results available on the Electoral Commission website.]

The 2011 Te Tai Tokerau by-election will be held today. This is the fourth by-election to be held since the 2008 general election, which, whilst not a record, is certainly the most during the last ten terms of parliament.

To date I am aware of only one poll in the electorate, which was the Native Affairs-Baseline poll which had Hone Harawira (Mana Party) on 41%, Kelvin Davis (Labour Party) on 40% and Solomon Tipene (Maori Party) on 15%.

As with the previous 2009 Mount Albert by-election, 2010 Mana by-election and 2011 Botany by-election I have attempted to predict the outcome of the election and the share of the votes won by each of the major or minor NZ political party’s candidates using a Monte Carlo simulation of 50,000 NZ general elections based on recent political polling results. The results for the Te Tai Tokerau by-election are determined using the Uniform National Swing model of electorates. The results of the simulation are shown in the table below, and the results of the 2008 General Election for the Te Tai Tokerau electorate are included for reference.

Simulated results of 2011 Te Tai Tokerau by-election

Table showing simulated results of 2011 Te Tai Tokerau by-election, as calculated on 25 June 2011.

So that is a guaranteed win for Solomon Tipene and the Maori Party!

It goes without saying that the whole prediction is an excercise in futility given that the recently-formed Mana Party didn’t exist at the previous election, and so we don’t have any baseline off which to predict their performance. In fact the discrepancies with the one opinion poll quoted above are so great that, unlike the recent Mana and Botany by-elections, the simulation has practically no predictive power whatsoever. It isn’t even obvious what would count as a “good” result for each of the candidates (although winning the by-election should probably be considered a “good” result). I guess this post therefore serves as another warning against taking the results of Uniform National Swing predictions too seriously.

The only other quantitative predictions for the Te Tai Tokerau by-election that I’m aware of are from New Zealand futures market iPredict, who as of 17:50 (see screen captures below) are giving the Mana Party a 78.0% chance of winning, the Labour Party an 18.7% chance of winning, and any other candidate a 2.0% chance of winning (probabilities do not necessarily have to add to 100% due to the bid/ask spread). iPredict also predict that the Mana Party candidate will win 43% of the vote, the Labour Party candidate will win 41% of the vote, the Maori Party candidate will win 17% of the vote.

I’m not aware of anybody else making quantitative prediction on the results, but if you know of anybody, or if you would just like to take a punt, then feel free to leave a comment below.

iPredict's Te Tai Tokerau by-election winner predictions

Screen capture of iPredict's Te Tai Tokerau by-election winner predictions, as of 17:50 on 25 June 2011.

iPredict's Te Tai Tokerau by-election vote share predictions

Screen capture of iPredict's Te Tai Tokerau by-election vote share predictions, as of 17:50 on 25 June 2011.

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A fairly slow period for political polls. In the month or so since the last update we have seen just two polls from Roy Morgan Research (1, 2). The polls showed some fairly large fluctuations, with support for Labour in particular jumping from 28% to 36%, and then back to 30%. After averaging out the results though, there doesn’t seem to be any statistically significant changes for any of the parties. It looks like the movement in the last three Roy Morgan polls was just statistical noise, albeit at the top end of what we could expect given the polling sizes.

The updated polling averages now have National on 52.4% +/- 1.8% and Labour on 32.2% +/- 1.6%. The Greens are down slightly to 6.8% +/- 0.9%, and ACT appear up slightly to 2.3% +/- 0.6%

As usual, the two graphs below summarise the polling averages for the party vote after the new poll. The horizontal axes represent the date, starting 60 days before the 2008 NZ General Election, and finishing on the present day. The solid lines with grey error bands show the moving averages of the party vote for each party, and circles show individual polls with the vertical lines representing the total errors.

Party vote support for the eight major and minor NZ political parties

Party vote support for the eight major and minor NZ political parties as determined by moving averages of political polls. Colours correspond to National (blue), Labour (red), Green Party (green), New Zealand First (black), Maori Party (pink), ACT (yellow), United Future (purple), and Progressive (light blue) respectively.

Party vote support for the six minor NZ political parties

Party vote support for the six minor NZ political parties as determined by moving averages of political polls. Colours correspond to Green Party (green), New Zealand First (black), Maori Party (pink), ACT (yellow), United Future (purple), and Progressive (light blue) respectively.

As always, please check the Graphs page for further simulation results.

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