Feeds:
Posts
Comments

Archive for the ‘2011 NZ General Election’ Category

Final effective party lists for the 2011 NZ General Election, based on candidate election probabilites post below.

This lists order candidates for each party by the probabilty of being elected to parliament as the lowest ranked successful list candidate for their party. In other words, the probability that a party vote for this party will go towards electing this candidate.

For more information please refer to the original effective party lists post.

Effective party list for the National party.

Effective party list for the National party.

A vote for the National party is a vote for Joanne HAYES (41%), Claudette HAUITI (35%), Sam COLLINS (14%), or Aaron GILMORE (5%).

Effective party list for the Labour party.

Effective party list for the Labour party.

A vote for the Labour party is a vote for Deborah MAHUTA-COYLE (36%), Stuart NASH (24%), Rick BARKER (24%), Carmel SEPULONI (7%) or Brendon BURNS (6%).

Effective party list for the Green party.

Effective party list for the Green party.

A vote for the Green party is a vote for David HAY (63%) or James SHAW (35%).

Effective party list for the ACT party.

Effective party list for the ACT party.

A vote for the ACT party is a vote for Don Brash (71%) or Catherine ISAAC (26%).

Effective party list for the Maori party.

Effective party list for the Maori party.

A vote for the Maori party is a wasted vote, in the sense that it will not help elect anybody to parliament because of the Maori party overhang.

Read Full Post »

Shown below are the updated Candidate Election Probabilities based on tonight’s polling update. Please click to embiggen. For an explanation of the methodology please see the original post on individual candidate election probabilities.

(Should also point out that I’ve made a couple of manual tweaks to the list this time, as it is the last one to be published before the election. I have given the Progressive party’s votes in Wigram to the Labour candidate, who is widely considered to be the most likely to benefit from Jim Anderton not standing, and have given votes to Hone Harawira in Te Tai Tokerau to reflect his likelihood of winning there.)

  1. Rank: From 0 to 899, gives the respective candidate’s relative likelihood of being elected, and is ordered firstly by probability to be elected, and then by party code and list ranking where there is a tie.  Candidates are shown in the table ordered by “rank”.
  2. Party Code : A unique code for each political party.  Parties are numbered 0~7, and ordered firstly by the number of seats won in the 2008 NZ General Election, and secondly by the number of party votes received.
  3. Party
  4. List Ranking
  5. Name: The name of the candidate (as given on the Elections New Zealand website, where available).
  6. Electorate: The electorate the candidate will stand in. For list-only candidates this will read “list only.”
  7. Electorate Code : A unique code for the electorate.  Electorates are numbered in alphabetical order, with general electorates (#0 ~ #62) preceding Maori electorates (#63 ~ #69). If the candidate is a list-only candidate candidate this code will take the value -1.
  8. Elect. 08: Blank, for the moment.
  9. Prob. Electorate: Probabilty of being elected to parliament as an electorate candidate.
  10. Prob. List: Probabilty of being elected to parliament as a list candidate.
  11. Prob. Combined: Combined probabilty of being elected to parliament as an electorate candidate.
  12. Prob. Last: Probabilty of being elected to parliament as the lowest ranked successful list candidate for their party.  In other words, the probability that a party vote for this party will go towards electing this candidate.
Probabilities for each candidate to be elected to Parliament

Probabilities for each candidate to be elected to Parliament through their electorate, through the party list, and the overall combined probability. (PNG, 760kB)

Read Full Post »

The last two polls to make it out in time for the election are the overnight Roy Morgan Research poll and this morning’s Herald-Digipoll

The updated polling averages now have National on 51.4% +/- 0.5%, Labour on 27.1% +/- 0.5%, the Greens on 11.2% +/- 0.3%, NZF on 3.7% +/- 0.2%, ACT on 1.9% +/- 0.2% and the Maori Party on 1.1% +/- 0.2%. Increases for the Greens and New Zealand First are statistically significant relative to the previous update from last night, although only just. Changes for others not statistically significant.

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 day of the 2011 NZ General Election (26 November 2011). 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), United Future (purple), and Progressive (light blue) 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), United Future (purple), and Progressive (light blue) respectively.

As far as the election results go, National is still predicted to win an outright majority.

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

Please also check back later this evening, as I will have a new post with the updated candidate election probabilites and effective party lists.

Read Full Post »

I’ve spent a few weekends over the last month or so driving around the southern North Island, taking in both Kapiti and Wairarapa sides of the Tararua ranges, and have been doing a bit of a billboard count as I went.  Should point out that the following takes in major and minor state highways and some properly rural stuff, in addition to the greater Wellington region:

  • National: 29 (54% +/- 7%)
  • Labour: 12 (22% +/- 6%)
  • Green: 5
  • ACT: 0
  • Maori: 4
  • NZF: 4

Okay, so it’s not exactly a scientific survey, but the thing that struck me was that the proportion of National and Labour billboards was within the margin of error of their recent polling.  This was true over pretty much any 50km stretch and didn’t seem to depend on electorate, and I started wondering about cause and effect.  Are National doing well in the polls because of all their billboards?  Or are the number of billboards are reflection of their funding and volunteer numbers?  I suspect it could be a bit of both.  (I should also note that this is just the number I saw from the driver’s seat.  I hear there are a few Labour billboards sitting down side streets, or facing perpendicular to the road, which I probably missed.)

The other thing that stood out was the difference in content:

  • The National party was running a variety of billboards, and they would change from week to week.  Candidate billboards, billboards with PM and National party leader John Key, as well as stuff trying to introduce policy (“Building better roads and …”) and general, ambiguous “For a Brighter Future” stuff.
  • The Labour party billboards were singularly introducing electorate candidates.  Nothing else.  I saw a large black sign that said “STOP ASSET SALES” which may have been Labour, but it wasn’t 100% obvious.
  • The Green party billboards were of the appeal-to-emotion type: pictures of happy people with the phrase “For a Richer NZ”.  No policy, no candidates, no party-leaders.

I just thought the differences were interesting, and the overall impression was that the National campaign is much more determined and better executed.

For a different conclusion, please see Kiwi Politico.

Read Full Post »

Shown below are the updated Candidate Election Probabilities based on tonight’s polling update. 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.

Probabilities for each candidate to be elected to Parliament through their electorate, through the party list, and the overall combined probability. (PNG, 770kB)

Will follow tomorrow with some analysis, but for the mean time there are two points that stand out:

  1. With the number of recent polls the margins of error on the polling averages has shrunk, meaning there are less candidates on the above list.  There are only about 140 or so candidates with a chance of winning a seat, so if the polls are correct there won’t be too many surprises on election night.
  2. The results for Labour (but not so much for National) are heavily dependent on the electorate results, which aren’t necessarily modelled realistically given that National are polling so much higher than they were at either of the two previous general elections.  Many of Burns (#29, Christchurch Central), Tirikatene (#45, Te Tai Tonga), Hipkins (#42, Rimutaka), Lees-Galloway (#37, Palmerston North), Wood (#32, list only), Chadwick (#34, Rotorua), O’Conner (West Coast-Tasman, electorate only) and Sutton (#35, Waikato) are in for a disappointing night, but it’s difficult to tell exactly which at the moment.  For more info see Kiwiblog.

Will calculate the effective party lists tomorrow before the 12PM blackout, but for the moment they look as follows:

  1. National: Hayes (#64, Dunedin South), Hauiti (#63, Mangare), Collins (#66, Wigram)
  2. Labour: Nash (#27, Napier), Burns (#29, Christchurch Central), Mahuta-Coyle (#26, Tauranga)
  3. Green: Shaw (#15), Hay (#16)

Read Full Post »

Pundit has a post up by Rob Salmond looking at the trends from a linear regression to recent poll results, which they then extrapolate to the election.  They have National winning 50.8% of the vote at the election, Labour, 24.8% and the Greens 14.6%.  The results are pretty much within the margin of error of the predictions here, but the whole concept of doing a linear regression and extrapolating the results forward is a bit sloppy.  For some reason it just reminds me of the statistical analysis I’ve come to expect from The Standard.

There is a lot wrong with this approach, but instead of going through it I will just quote another blog post from earlier this year.  From Pundit.  By Rob Salmond.

When a pundit says “if this trend continues to the election,” stop listening

The original piece was a must-read.

Read Full Post »

There has been a bit of hysteria the last few days about dire consequences if New Zealand First should be returned to parliament. See PM John Key on Stuff, or the Vote For Change campaign’s highly ignorable press releases, for example.

So what’s going on? A couple of recent polls have the NZF party closing in on the 5% threshold, and the probability of NZF being returned to Parliament has shot up to about 50% on iPredict, from about 15% just over a week ago.

Probability of New Zealand First being returned to parliament according to iPredict, as of evening of 20 November, 2011.

Probability of New Zealand First being returned to parliament according to iPredict, as of evening of 20 November, 2011.

On top of this, NZF leader Winston Peters has made a point of saying he won’t go in to coalition with anybody, or support anybody with supply and confidence, leading observers to assume that if NZF wins seats in parliament this election everything will turn to custard and we will be having another election in the next few months.

So what would actually happen if NZF were returned to parliament?

The current situation.

To figure this out we run a series of simulations, firstly based on the current polling avereges. We call this “Situation #0”. It looks something like this:

Histogram showing the total number of seats National are expected to win in parliament under Situation #0. National are expected to win 65.4 +/- 0.8 (RMS) seats.

Histogram showing the total number of seats National are expected to win in parliament under Situation #0. National are expected to win 65.4 +/- 0.8 (RMS) seats.

Histogram showing the total number of seats Labour are expected to win in parliament under Situation #0.  Labour are expected to win 35.4 +/- 0.8 (RMS) seats.

Histogram showing the total number of seats Labour are expected to win in parliament under Situation #0. Labour are expected to win 35.4 +/- 0.8 (RMS) seats.

Keep in mind that a party would need 63 seats to win a majority:

Histogram showing the number of seats needed to form a majority in Parliament under Situation #0. The winning party or coalition will most probably need 63 seats in Parliament to form a majority.

Histogram showing the number of seats needed to form a majority in Parliament under Situation #0. The winning party or coalition will most probably need 63 seats in Parliament to form a majority.

So National is therefore almost guaranteed an outright majority in the house:

Scenario analysis for Situation #0. The bar graph shows the probabilities for different possible outcomes for a NZ General Election.  The National Party would have a roughly 99.98% chance of governing alone, a roughly 0.02% chance of governing as leader of a National-ACT coalition, and a 0% chance of governing as leader of a National-ACT-United Future coalition. There is a 0% chance that the Maori Party would hold the balance of power in Parliament.

Scenario analysis for Situation #0. The bar graph shows the probabilities for different possible outcomes for a NZ General Election. The National Party would have a roughly 99.98% chance of governing alone, a roughly 0.02% chance of governing as leader of a National-ACT coalition, and a 0% chance of governing as leader of a National-ACT-United Future coalition. There is a 0% chance that the Maori Party would hold the balance of power in Parliament.

So there you have it.

What if NZF makes 5%?

And what would happen if NZF just makes the 5% threshold? Firstly lets simulate this by assuming that NZF takes the same number of votes from National and Labour such that they get exactly 5%. We call this “Situation #1”. Under Situation #1 NZF would win exactly 6 seats. And the other parties?

Histogram showing the total number of seats National are expected to win in parliament under Situation #1. National are expected to win 62.1 +/- 0.8 (RMS) seats.

Histogram showing the total number of seats National are expected to win in parliament under Situation #1. National are expected to win 62.1 +/- 0.8 (RMS) seats.

Histogram showing the total number of seats Labour are expected to win in parliament under Situation #1. Labour are expected to win 33.2 +/- 0.8 (RMS) seats.

Histogram showing the total number of seats Labour are expected to win in parliament under Situation #1. Labour are expected to win 33.2 +/- 0.8 (RMS) seats.

So with NZF taking 1% or so of the vote from each of National and Labour and winning 6 seats, National and Labour would respectively be 3.3 and 2.2 seats worse off. The fallout is not just limited to those two parties either; the Greens, for example, would be 0.5 seats worse off. And who would form the government?

Scenario analysis for Situation #1. The bar graph shows the probabilities for different possible outcomes for a NZ General Election.  The National Party would have a roughly 25.1% chance of governing alone, a roughly 70.5% chance of governing as leader of a National-ACT coalition, and a roughly 4.1% chance of governing as leader of a National-ACT-United Future coalition. There is a 0.3% chance that the Maori Party would hold the balance of power in Parliament.

Scenario analysis for Situation #1. The bar graph shows the probabilities for different possible outcomes for a NZ General Election. The National Party would have a roughly 25.1% chance of governing alone, a roughly 70.5% chance of governing as leader of a National-ACT coalition, and a roughly 4.1% chance of governing as leader of a National-ACT-United Future coalition. There is a 0.3% chance that the Maori Party would hold the balance of power in Parliament.

So if NZF takes votes off National and Labour equally and makes the 5% threshold there is a much reduced chance of National getting a majority, but we would still have a National Prime Minister. Winston Peters wouldn’t be in a position to force another election.

What if the votes come exclusively from National?

And what would happen if NZF just makes the 5% threshold, and takes their extra votes exclusively from current National supporters. We call this “Situation #2”. Under Situation #2 NZF would still win exactly 6 seats, and National would be as follows:

Histogram showing the total number of seats National are expected to win in parliament under Situation #2. National are expected to win 61.2 +/- 0.8 (RMS) seats.

Histogram showing the total number of seats National are expected to win in parliament under Situation #2. National are expected to win 61.2 +/- 0.8 (RMS) seats.

Scenario analysis for Situation #2. The bar graph shows the probabilities for different possible outcomes for a NZ General Election. The National Party would have a roughly 4.4% chance of governing alone, a roughly 69.6% chance of governing as leader of a National-ACT coalition, and a roughly 21.1% chance of governing as leader of a National-ACT-United Future coalition. There is a roughly 5.0% chance that the Maori Party would hold the balance of power in Parliament (with a National-coalition advantage).

So if NZF takes votes solely off National and just makes the 5% threshold there is a much reduced chance of National getting a majority, but we would still most likely get a National Prime Minister, even without taking the Maori Party into consideration. Winston Peters almost certainly wouldn’t be in a position to force another election.

What if NZF makes 7%, and the votes come exclusively from National?

Now lets assume that NZF wins exactly 7% of the vote, with their extra votes coming exclusively from current National supporters. We call this “Situation #3”. Under Situation #3 the results would be as follows:

Histogram showing the total number of seats NZF are expected to win in parliament under Situation #3. NZF are now expected to win 8.7 +/- 0.4 (RMS) seats.

Histogram showing the total number of seats NZF are expected to win in parliament under Situation #3. NZF are now expected to win 8.7 +/- 0.4 (RMS) seats.

Histogram showing the total number of seats National are expected to win in parliament under Situation #3. National are expected to win 58.6 +/- 0.7 (RMS) seats.

Histogram showing the total number of seats National are expected to win in parliament under Situation #3. National are expected to win 58.6 +/- 0.7 (RMS) seats.

Scenario analysis for Situation #3. The bar graph shows the probabilities for different possible outcomes for a NZ General Election.  The National Party would have a 0% chance of governing alone, a roughly 0.4% chance of governing as leader of a National-ACT coalition, and a roughly 4.5% chance of governing as leader of a National-ACT-United Future coalition. There is a roughly 95.5% chance that the Maori Party would hold the balance of power in Parliament (still most likely with a National-coalition advantage).

Scenario analysis for Situation #3. The bar graph shows the probabilities for different possible outcomes for a NZ General Election. The National Party would have a 0% chance of governing alone, a roughly 0.4% chance of governing as leader of a National-ACT coalition, and a roughly 4.5% chance of governing as leader of a National-ACT-United Future coalition. There is a roughly 95.5% chance that the Maori Party would hold the balance of power in Parliament (still most likely with a National-coalition advantage).

So even under the rediculously optimistic scenario of NZF doubling their current support in the next six days, with the new support coming solely off National, the Maori party would still most-likely hold the balance of power in parliament.

And what would the Maori party do? Coalition with National, ACT and United Future? Or coalition with Labour, Greens, Mana and New Zealand First? Even assuming that the latter four parties were all on the same page (unfeasible, given recent statements from their leaders), would the Maori party favour them? Not likely if a three-party right-wing coalition had a numbers advantage over the four-party left-wing coalition. It would be far too easy (politically) for the Maori Party to go into a right-wing coalition, and extract some fairly heavy concessions whilst doing so.

Conclusion.

So, in summary, even if NZF win 7% of the vote, which is unlikely on current polling, the chances of them holding a balance of power and forcing another election are effectively zero. Anybody who suggests otherwise is just being a bit hysterical.

Read Full Post »

There has been a bit of talk lately about tactical voting in Epsom, and the “cup of tea” between PM John Key and ACT Epsom candidate John Banks has been in the news a bit.  So what’s going on?

The short version of the story is that in New Zealand, where we elect our Parliament under MMP, a party needs to either win 5% of the nationwide popular vote (party vote) or win an electorate seat to get seats in Parliament in proportion to their party vote. The current National party government’s coalition partner, the ACT party, won’t make the 5% threshold on current polling, and so the PM is in a position where he is motivated to throw the ACT party an electorate seat, the seat of Epsom to be precise.

So what happens if ACT do win Epsom?

Total seats won by ACT party, assuming they win Epsom.

Total seats won by the ACT party, assuming ACT win Epsom.

Total seats won by National party, assuming ACT win Epsom.

Total seats won by the National party, assuming ACT win Epsom.

This is the more likely situation at the moment: ACT win 1 electorate and 2.0 +/- 0.1 (RMS) total seats in Parliament. Under this scenario the National party would win 65.4 +-/ 0.8 (RMS) seats in parliament.

And what happens if ACT don’t win Epsom, and the National party candidate (Paul Goldsmith) wins instead?

Total seats won by ACT party, assuming National win Epsom.

Total seats won by the ACT party, assuming National win Epsom.

Total seats won by the National party, assuming National win Epsom.

Total seats won by the the National party, assuming National win Epsom.

In this situation the ACT party gets no seats in Parliament, and is 2.0 +/- 0.1 seats worse off. The plus-side for National is that they win 66.5 +/- 0.8 seats, and are now 1.1 seats better off.

You can do similar calculations for the other parties.  Here’s how everybody ends up if National win Epsom, relative to how they would have been if ACT had won Epsom:

  • National: +1 electorate seat, +0.1 list seats.  Overall +1.1 seats better off.
  • Labour: +0.6 seats.
  • Green: +0.3 seats.
  • ACT: -2.0 seats.
  • Maori: +0.0 seats.
  • NZF: +0.0 seats.
  • Overhang: +0.0 seats in Parliament.
  • (NB: rounding)

For those who wonder why Labour only gets 0.6 extra seats, vs. National’s 1.1, the answer is simple: Labour is polling just over half what National is polling in terms of the party vote. Regardless, if you ignore the probability of ACT going into coalition with Labour, Labour are still better off if National win Epsom than they are if ACT win Epsom.

This raises interesting questions regarding tactical voting for those in the Epsom electorate. Assuming that ACT will not hold a balance of power after the election and choose to go in to coalition with Labour, then Labour are better off if Paul Goldsmith (National candidate for Epsom) wins the seat, and John Banks (the ACT candidate) loses. Similar logic applies for the Greens, Mana, and NZF. ACT supporters obviously want their candidate to win. For Maori, United Future and National supporters the situation is a bit more complex, and depends on who is likely to win the election.

For that, please refer to the scenario analysis graphs below:

Scenario analysis for the most recent election simulation assuming ACT win Epsom.

Scenario analysis for the most recent election simulation assuming ACT win Epsom.

Total seats won by the the National party, assuming National win Epsom.

Total seats won by the the National party, assuming National win Epsom.

Looking at the two graphs, you might not notice too much difference. The first graph shows National with a 99.98% chance of winning a majority, and a 0.02% chaince of leading a National-ACT coalition. The second shows National with a 100.00% chance of winning an absolute majority, and a 0.00% chance of leading a National-ACT coalition. Either way, New Zealand gets a National Party Prime Minster.

So if you are a National, Maori or United Future party supporter, what is your preferred result? Based on current polling it would be option #2 above: National win Epsom.

(I should here point out the difference between tactics and strategy. On this blog, “tactics” refers to the short term: doing what is necessary to get the result you want from the next election. “Strategy” refers to a more long-term positional advantage. Pollsters are not in a position to comment on whether having ACT in Parliament would be good or bad for National, Maori and United Future supporters in the long term.)

The results of this hypothetical analysis are surprisingly simple: Labour, Green, Mana and New Zealand First supporters in Epsom, and an overwhelming majority of National, Maori and United Future supporters in Epsom should vote tactically for Paul Goldsmith. The National candidate should win in a landslide.

Read Full Post »

When I first published a post on the probabilities of being elected on a candidate-by-candidate basis last year I mentioned that the main motivation was that I hoped that people will be able to see which individual list candidate their party vote is likely to be counted for.

Closer to the 2011 General Election I will begin publishing “effective party lists” on a regular basis. These effective lists will show only those candidates on the cusp of winning a list seat for each party, and will hopefully give NZ voters a better idea of where their vote is going, and a more meaningful alternative to a quick glance at the top of the lists for each party which some seem to use now when deciding how to cast their votes.

I think this is still quite important information, and I want to make sure it is available publicly immediately before the 2011 General Election so that people can make a more-informed party vote. But recently another benefit has become obvious: helping parties to avoid the so-called “Tizard Problem.” Since Darren Hughes announced his resignation last week there has been speculation that Labour will ask the next highest placed list candidate, Judith Tizard, to stand aside in order to allow a lower ranked list candidate to filter through to Parliament. There were also suggestions on some blogs that the party didn’t want to stand list MPs in the by-elections for safe Labour seats in Mana and Mt Albert because that would have allowed Tizard back into Parliament, thus limiting their options for candidate selection for the by-elections.

I’m not sure how accurate these theories are of what the Labour Party strategists are actually thinking, and I’m not going to speculate, but if they are true, then they represent a massive failure on the part of those who determined the Labour Party List for the 2008 Election.

After a bit of thought I’ve decided that preventing a hypothetical “Tizard Problem” basically just involves figuring out the effective party lists for each of the parties. Specifically, figuring out who your party vote is going to help get elected is simply a case of figuring out who the lowest ranked list candidate to win a list seat for the party that you voted for is. And this is basically the same problem as figuring out who the highest ranked list candidate to not be awarded a seat is. This can be calculated from the results of the election simulation we use here to figure out which candidates get in to Parliament, and which miss out. The methodology is the same as that for the other simulations on this site.

By simulating a large number of elections based on current opinion polling, and counting up the number of times each party list candidate is the lowest-ranked list candidate to be elected for their party, we can see who the party votes for each party are going towards electing. The results are shown below for each of the eight major and minor NZ political parties, with the probability of a candidate being the lowest-ranked list candidate to be elected for their party shown under the heading “Prob. Last” in the right-most column. The effective party lists are ordered by decreasing values of “Prob. Last.” The party list rankings of the candidates shown at the tops of these lists correspond to the “sweet spots” on each respective parties list, in other words, the list rankings that could potentially result in a “Tizard Problem” for those parties during the next term of Parliament if they were to be filled by electorally unpopular candidates.

The first example is for the Green Party, one of the easier results to understand.

Effective party list for the Green Party

Effective party list for the Green Party.

First place on the Green Party effective party list is Steffan Browning, with list ranking #9 and standing in the Kaikoura electorate. He has a 0% chance of winning his electorate seat, a 79% chance of getting in on the list, and a 32% chance of being the lowest ranked Green party candidate to be elected. In other words, if you vote for the Green party with your party vote there is a 32% chance that your vote will go towards electing Browning. The effective party list then skips up and down the actual party list, with Mathers (list ranking #10), Hughes (#8) and Ward (#11) following. The reason Hughes (#8) is below Browning (#9) is because whilst he is slightly more likely to be elected, he is less likely to be the last person elected. For the same reason, highly-ranked list candidates such as co-leaders Metiria Turei and Russel Norman are almost guaranteed to be elected whether you vote for the Greens or not, and thus have low effective party list rankings of #10 and #11, respectively.

If you add up the numbers for “Prob. Last” in the far right column you will get 100% (give or take a bit of rounding error), which means there is a 100% chance that your party vote for the Green Party will go towards getting somebody elected from their list.

Next up is the Maori party.

Effective party list for the Maori Party

Effective party list for the Maori Party.

Nothing interesting is happening here, with the effective party list exactly matching the order of the actual party list, and candidates either winning an electorate seat or not being returned to Parliament. This is because of the overhang caused by the Maori Party, with the party winning more electorate seats than the total number of seats they would be entitled to based on their party vote.

If you add up the numbers for “Prob. Last” in the far right column you will get 0%, which means there is a 0% chance that your party vote for the Maori party will go towards getting somebody elected from their list. In other words, a party vote for the Maori Party is a guaranteed “wasted” vote.

The examples for both the Green and Maori parties are easy enough to understand intuitively, but things get a bit more complicated when you look at parties that may win both electorate and list seats, such as the ACT party.

Effective party list for the ACT Party

Effective party list for the ACT Party.

First up is John Boscawen, with a 31% chance of being the lowest ranked list candidate elected, followed by Roger Douglas (5%) and Heather Roy (0%, rounded down). In fourth place on the effective list is party leader Rodney Hide, with 0% chance of being the lowest ranked candidate. The reason for this is that ACT Party Leader Hide, like Maori Party leader Pita Sharples, will either win his electorate seat or not return to Parliament. Unlike #2 – #4 on the ACT party list he has no chance of winning a list spot on current polling (where ACT are well below the 5% threshold).

If you add up the numbers for “Prob. Last” in the far right column you will get 36%, which means there is a 36% chance that your party vote for the ACT party will go towards getting somebody elected from their list. In other words, there is a 74% chance that a party vote for the ACT party will be a wasted vote. More specifically, there is a 4% chance that a party vote for the ACT party will be a wasted vote because Hide will lose Epsom and nobody from ACT will be elected, and there is a 70% chance that a party vote for the ACT party will be a wasted vote because although Hide wins Epsom, the party does not get enough party votes for somebody else to join him as a list MP.

The three patterns above explain most of the possible outcomes as far as effective party lists go, and for the other parties the effective party lists just behave as a combination of the patterns seen above. Next is National:

Effective party list for the National Party

Effective party list for the National Party.

The sweet spot on the list here belongs to Ravi Musuku (Mt. Albert, list ranking #63), Mita Harris (Mangere, #62) and Marc Alexander (Wigram, #60). These are the people your party vote will be going towards getting elected if you party-vote National.

What happened to those on the list ranked #61 (Malcolm Plimmer) and #64 (Jonathan Young)? They’re on the effective list as well, just a bit further down. The reason is that for them to be the lowest ranked National candidates to win a list seat they would have to first lose their electorate seats, New Plymouth and Palmerston North, which are National-leaning seats. (Yes, I’m aware that New Plymouth and Palmerston North are not traditionally considered “National-leaning seats.” The individual electorate results are modeled on the principle of Uniform National Swing). This is why you have to take the results in individual electorate seats into account when trying to figure out where your party vote is going!

Next is the Labour Party:

Effective party list for the Labour Party

Effective party list for the Labour Party.

A vote for the Labour Party is most likely going to go to Damien O’Conner (West Coast-Tasman, #32), Grant Robertson (Wellington Central, #34), or Iain Lees-Galloway (Palmerston North, #36). All three face a difficult battle to win their electorate seats on current polling.

Judith Tizard is still on the effective party list in #9 position, with a 5% chance of being the lowest ranked Labour list candidate to win a list seat in Parliament.

Next up, the Progressive Party and the United Future Party:

Effective party list for the Progressive Party

Effective party list for the Progressive Party.

Effective party list for the United Future Party.

Effective party list for the United Future Party.

These two show a pattern very similar to that shown by the ACT Party. In all three cases you have a party leader with a non-100% chance of winning an electorate seat, and a party that is not guaranteed to break the 5% threshold to get seats without the electorate waiver, which results in a non-zero possibility of a wasted vote. In all three cases the wasted vote can be caused by the leader failing to win their electorate seat, or by winning their electorate seat but the party not having a high enough party vote to elect other list MPs along with them.

Finally, the New Zealand First Party.

Effective party list for the New Zealand First party

Effective party list for the New Zealand First party.

Another fairly intuitive result. With NZF polling about 4% at the moment, they are within a margin-of-error or so from breaking the 5% threshold, which, like the Green Party, would see them win list seats even though they are not predicted to win an electorate seat. The sweet spot on the NZF party list corresponds to candidates with list rankings of #6 and #7.

Obviously the results above are purely hypothetical, given that they are based on old party lists from the 2008 General Election that have been modified arbitrarily to take account of retirements and so on during the current term of Parliament. I look forward to whipping up new lists when the finalised party lists for the 2011 General Election are made public.

Read Full Post »

A few days ago Jeanette Fitzsimons announced her retirement from Parliament, effective February 11th 2009. Ms Fitzsimons will be replaced by Gareth Hughes, who was ranked #11 on the Green Party List for the 2008 NZ General Election.

The implications of this move for the other major and minor NZ political parties are potentially far greater than many would suspect of a simple swapping of list members, something that has already happened three times in the last year alone (Labour list MP Michael Cullen, National list MP Richard Worth, and Green list MP Sue Bradford have all resigned in the last 10 months.) The reason for this is that the new Green MP Gareth Hughes stood for the Ohariu seat in the 2008 General Election, where he had the effect of splitting the vote and allowing United Future MP Peter Dunne’s party in to Parliament through the MMP electorate waiver (Mr. Dunne did not bring any list MP’s with him, however.) Assuming Gareth Hughes contests Ohariu again in a 2011 General Election he will be campaigning as an MP, not as an outsider, which should change the dynamics of the race. BKD has a multi-part series (prologue, part 1, part 2, part 3, part 4, part 5) looking at how this affects the race in Ohariu.

Firstly, before starting with any analysis, I thought I should mention the latest election simulation results from Ohariu: based on the latest polling averages the United Future candidate (presumably current MP Peter Dunne) is expected to win 73.2% of the time, the National Party candidate (presumably current list MP Katrina Shanks) is expected to win 26.7% of the time, and the Labour Party candidate (presumably current list MP Charles Chauvel) is expected to win 0.1% of the time. I wouldn’t put too much faith in these numbers though, as they are computed partially by comparing the current polling averages to the results of the 2005 and 2008 NZ General Elections, and as National as polling considerably higher than they were then the model is behaving a bit pathologically. Additionally, the model does not take the merits of individual candidates into account, instead calculating probabilities for “generic” candidates from each party, and so doesn’t take into account any changes in the dynamics that will occur due to Mr. Hughes’ presence in Parliament.

Rather than focusing on trying to calculate the probabilities for each of the above candidates, I would instead like to investigate the results of an election under two simple scenarios; firstly with Peter Dunne winning Ohariu, and secondly with him losing. The implications of the first scenario are calculated using a MC Simulation of 50,000 NZ Elections with Dunne winning Ohariu. The resulting distributions of seats for National and Labour are shown below.

Histogram showing the total number of seats National are expected to win in parliament under Scenario #1

Histogram showing the total number of seats National are expected to win in parliament under Scenario #1, with Peter Dunne winning the Ohariu electorate. National are expected to win 66.5 +- 1.8 (RMS) seats.

Histogram showing the total number of seats Labour are expected to win in parliament under Scenario #1

Histogram showing the total number of seats Labour are expected to win in parliament under Scenario #1, with Peter Dunne winning the Ohariu electorate. Labour are expected to win 38.6 +- 1.6 (RMS) seats.

Under this scenario, National are expected to pick up a total of 66.5 +- 1.8 seats in Parliament, and Labour a total of 38.6 +- 1.6 seats.

The implications of the second scenario are calculated analogously using a MC Simulation of 50,000 NZ Elections with Peter Dunne not winning Ohariu. The resulting distributions of seats for National and Labour are again shown below.

Histogram showing the total number of seats National are expected to win in parliament under Scenario #2

Histogram showing the total number of seats National are expected to win in parliament under Scenario #2, with Peter Dunne not winning the Ohariu electorate. National are expected to win 66.8 +- 1.8 (RMS) seats.

istogram showing the total number of seats Labour are expected to win in parliament under Scenario #2

Histogram showing the total number of seats Labour are expected to win in parliament under Scenario #2, with Peter Dunne not winning the Ohariu electorate. Labour are expected to win 38.8 +- 1.6 (RMS) seats.

At a casual glance, it may not be easy to see the difference between these two graphs and the ones shown earlier. However, under this scenario, National are expected to pick up a total of 66.8 +- 1.8 seats and Labour a total of 38.8 +- 1.6 seats. The slightly counter-intuitive result of the study is that if Peter Dunne loses the Ohariu seat both National and Labour are individually expected to be slightly better off, and this result holds regardless of which party’s candidate picks up Ohariu in the event that Mr. Dunne loses. The reason for this outcome is that if Peter Dunne loses Ohariu, his party does not achieve the electorate waiver, and as they are also unlikely to acheive the 5% party vote threshold they end up with no seats in Parliament. This effectively creates an extra list seat for National and Labour to fight over. The probability of it falling to one party or the other (or to a minor party) is roughly proportional to their respective party vote totals. The actual results are shown in the table below to two decimal places:

Comparison of total number of seats won in Parliament by each party for two different scenarios

Comparison of total number of seats won in Parliament by each party for two different scenarios; Peter Dunne wins Ohariu, and Peter Dunne loses Ohariu. The right-most column shows the expected difference for each party between the two scenarios.

This raises an interesting problem with regards to election strategy in the Ohariu electorate. If United Future were equally capable of going into coalition with either a Labour-led or National-led coalition, then Labour would be slightly better of if Peter Dunne won the seat, and National slightly worse off. However, as Peter Dunne has made clear, United Future would not be interested in going into coalition with Labour, and so therefore the opposite applies. Labour’s counter-intuitive goal for the Ohariu electorate in the 2011 NZ General Election is not to win, but rather to make sure that the United Future candidate (or ACT or Maori Party candidates, if applicable) do not win. To do otherwise, and vigorously contest the electorate and risk splitting the vote three or more ways, as they did in the 2008 General Election, would be a massive tactical and strategic blunder, and would indicate a poor understanding of the MMP electoral system. Of course, the above conclusion is of limited importance if the the Labour Party are unable to close the 22% point polling gap between themselves and National, but could be crucial in determining the results of a closer election.

Read Full Post »