Polling Update, 20 March

Apologies for the lack of recent updates.

Since the last update three and a half months ago we have seen 13 new polls: eight of the regular fortnightly polls from Roy Morgan, two from TV3-Reid Research, two from One News-Colmar Brunton, and one from Herald-Digipoll. The updated Kiwi Poll Guy polling averages have National on 52.0% +/- 1.7%, Labour on 33.3% +/- 1.6%, and the Greens on 7.5% +/- 0.9%, all virtually unchanged over the past three and a half months.

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 at the date of 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 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.

Also shown below are the updated Candidate Election Probabilities. Please click to embiggen. For an explanation of the methodology please see the original post on individual candidate election probabilities.

Probabilities for each candidate to be elected to Parliament through their electorate, through the party list, and the overall combined probability.

There haven’t been too many big changes since the last update in September 2010. It’s worth reiterating that these results are calculated from hypothetical party lists based on those used at the 2008 General Election, with a few common sense changes made to account for retirements and so on. The most recent change is the removal of Labour candidate Darren Hughes and a replacement with a dummy candidate, “LAB-41-Otaki,” who will contest the Otaki electorate with a presumed #41 list placing. All other Labour candidates with list placings of #17 to #41 have been bumped up one place.

For ease of viewing, the results for candidates serving as electorate MP’s in the 49th Parliament are also shown below, ordered by their electorate number.

Probabilities for reigning electorate candidates to be elected to Parliament through their electorate, through the party list, and both.

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2011 Botany By-Election

The 2011 Botany by-election will be held today.

As with the 2010 Mana 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 held today based on recent political polling results. The results for the Botany electorate 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 Botany electorate are included for reference.

Table showing simulated results of 2011 Botany by-election, as calculated on 5 March, 2011.

As long as the Uniform National Swing assumption is correct there is realistically no way that the National candidate can get anything less than 50% of the vote. It is worth mentioning that the model used for the simulation does not know that there is no candidate standing from the Green, Maori, United Future, New Zealand First or Progressive parties, which is why the vote estimates for those parties are non-zero

The usual caveats mentioned in the previous Preditions post for the 2010 Mana By-election still apply, so as always, I’m not going to take responsibility for them if they are significantly out, and conversely I will not be taking any credit if they prove accurate.

As for today’s Botany by-election, the only other predictions of the result of the election that I am aware of are from New Zealand futures market iPredict, who as of 18:30 are giving the National candidate a 100.0% chance of winning and the Labour candidate a 1.0% chance of winning (probabilities do not necessarily have to add to 100% due to the bid/ask spread.) 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.

[UPDATE] Results are now available at the Elections NZ website.

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