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Archive for March, 2012

In the first post-election update we have five new polls to work with, four from Roy Morgan Reasearch (1, 2, 3, 4) and a TV3-Reid Research poll.

The updated polling averages now have National on 47.6% +/- 1.3%, Labour on 29.6% +/- 1.2%, the Greens on 12.8% +/- 0.8% and NZF on 4.8% +/- 0.5%.

The first point to note is that these numbers are a lot closer to the actual 2011 election result than they are to the final pre-election polling update. What happened? One possible explanation is that a significant minority of voters made up their minds on who they would vote for at the 2011 election a day or so beforehand – too late to show up in any of the polls – and haven’t changed their support since. It seems a bit too suspicious though. I can’t think of any other obvious explanations.

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 raw statistical 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), and United Future (purple), respectively.

Party vote support for the Green party

Party vote support for the Green party as determined by moving averages of political polls.

Party vote support for the five minor NZ political parties

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

As always, please check the Graphs page for further simulation results. Unfortunately, though, because there have been only five polls in the last three months the margins of error have blown out, and the graphs aren’t particularly meaningful. In addition, you will notice a strange double-peaked graph for the number of seats National are expected to win. This is a result of unpredictability in whether or not NZF make the 5% threshold, and the graph is basically the sum of two Gaussians: one for when NZF gets over 5% and one for when they get less than 5%. If NZF continues to hover around the 5% mark I will have to think up a better way to present these results. Note also that it is pretty much impossible to predict who would be in government from the recent polls, due, again, to the large margin of error.

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