Reading the Political Tea Leaves

Despite mentioning tea in the title, this post is about opinion polls, not the ACT of drinking tea.

There are a number of sites that maintain graphs of New Zealand political polls, notably Rob Salmond at Pundit and, curiously, Wikipedia. Wikipedia post their data in tabular form, and provide the code for R underlying the creation of their graphs, allowing anyone with certain degree of geek cred to have a hack (ie, me). Yesterday, someone on wikipedia requested an updated version focussing only on more recent polls, which I had a go at, including making the fit line a bit more sensitive to change.

Changing the sensitivity of the fit line, makes it seem like there more movement than there has been in a while, and this graph was subsequently featured on the DimPost and then the Listener.

The next question was about whether the different polling parties differentially contribute to such a rolling poll. Their sample sizes are pretty uniform, at around 800. Roy Morgan contribute over half (68 of 121) with their poll regularly conducted over several days. 3 News Reid Research have fewer polls (16) but all conducted on a single day.

But how do the different parties fare in the polls (in order of polling).

Firstly, you can really get a sense from this graphic how much more regular Roy Morgan are, and their estimates are pretty consistently low, relative to the other pollsters. 3 News Reid Research is fairly consistently high. However, in the latest few polls, they have had some lower numbers for National.

3 News Reid Research is consistently lower on Labour, which combined with the above, suggests they favour National relative to the other pollsters. The Herald Digipoll has higher values for Labour most of the time.

The Herald Digipoll and ONE News Colmar Brunton are consistently lower for the Greens than other pollsters. However, in the most recnet polls, Herald Digipoll and ONE News Colmar Brunton both show much higher numbers than usual for the Greens.


  • There is definitely variation attributable to the pollsters.
  • It does seem like there is some change, at least with the polls. Whether this translates to anything meaningful for next Saturday, who knows. I plan to add ACT and NZ First later for completeness.
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Warmth from the sun

The other week, Cr Fliss Butcher suggested that there should be a ban on south-facing homes in Dunedin. Predictably (as can be seen in the comments thread in the link), this has been met with a hail of derision, but also some support. Personally, I think New Zealand building standards seem to be always out of date. Houses that were built as little as 10 years ago seem embarrassingly bad by current standards because of this. It was only in 2008 that double glazing became sort of mandatory, and many houses from the 90s (and some even up until 2008) have embarrassingly little insulation.

There are already rules on south, east and west facing glazing; if a house has more than 30% of its glazing on these walls, thermal modelling is required. This seems a more nuanced approach than simply banning south-facing homes. However, as always it seems that the rules could be more aggressive. I think that if you can afford to build a new house, then you can afford to spend a little more money to make sure that you are building a real asset. In essence, if you are going to build a new house in Dunedin, you may as well build a bloody warm one.

Research in Dunedin by economist Dr Paul Thorsnes backs this up. Houses built after 1978 (when insulation first became compulsory), command a hefty price premium relative to pre-insulation era houses. Similarly, houses that receive more sun in mid-winter are worth more than houses that receive less sun. This effect is particularly profound for pre-insulation era houses; a 3.9% increase for each additional hour of mid-winter sun. Perhaps unsurprisingly, Thorsnes lives in a sun-trap property.

But this is also a tale of how far we have come. When Austrian refugee architect Ernst Plischke designed a house in Christchurch c.1940, it was initially rejected because it did not have any* south facing windows. The issue was, of course, that the street was to the south, and under the rules of the time, the house had to address the street. The solution was eventually to add a few windows.

Fast forward 50-60 years, and the idea of an L-shaped house, opening to the sun and an outdoor living space is now taken as an almost given. The design seems surprisingly contemporary, as do some of Plischke’s other designs, such as the house he designed for Bill Sutch in Wellington, below.

*I’m pretty sure the design actually had none, and that he added some small windows, but I’m having to rely on my memory of this exhibition: ERNST PLISCHKE – ARCHITECT, City Gallery, Wellington, 5 September-28 November 2004.

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Shower Water Heat Recovery, Green Stars, and loan schemes

Several new University of Otago buildings have been constructed to 5 Star Green Building ratings: rainwater harvesting, grey water for flushing toilets, and lots of other energy efficiency features. This seems very laudable, except I’ve been extremely dubious about the merit of the shower water heat exchangers in the Hunter Centre.

The idea is that the warm water going down the drain pre-heats the water going to the shower, so less energy is used to heat that water for the same warmth of shower. This seems like a fantastic and practical idea, and according to the propaganda of the people that sell them, can easily save 25-40% of hot water heating costs (GFX, Vaportec). Except who showers in a building full of tutorial rooms? In fact, the demand has been so overwhelming, that the showerheads in the Hunter Centre have been removed.

Equally laudably, the Dunedin City Council is planning to provide loans to install solar hot water heating. Dunedin isn’t the best place in the country for solar hot water (although it *does* work). It would also seem sensible to provide loans for hot water heat pumps, as in Dunedin they are at least as effective as solar hot water. This is in part because during winter, solar hot water needs an electrical ‘top up’.

In contrast to solar hot water ($5000-$10,000) or hot water heat pumps ($5000), a heat exchanger for the grey water from the shower is closer to $700. They can be easily retrofitted to many existing houses (you merely need underfloor access; they are more efficient installed vertically, but can be installed horizontally), but can also be used in conjunction with solar or heat pump systems — and would effectively reduce the size of system that needs to be installed. They are also entirely compatible with gas hot water systems.

Simple, easy to install, and comparatively cheap. I would challenge the Dunedin City Council to not just provide loans for their installation, but also to see if they can get a discount for a bulk order. I’m ready to forgive the Hunter Centre: Even if no-one has ever had a shower there, it may be that getting the idea out there is what matters.

UPDATE: I’ve had a trawl through the published literature. There is not a great deal out there, but this paper argues that drainwater heat recovery is more cost effective than solar hot water heating, and there is sufficient evidence to show that these systems work.

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Why cash and buses don’t mix

One of the things that causes public transport to fail is when it starts to run late as passengers take too long to load.

The perfect opposite of this is the Hong Kong MTR (underground). All platforms have screen doors (so you can’t fall on the tracks, or be pushed). This also means you know where the train door is going to be. Now, in the image below, you can see some arrows on the platform. Basically, the white arrows encourage waiting passengers to wait at the sides of the doors, and green arrow indicates that exiting passengers go straight through the middle. Being Hong Kong, this works pretty well, and so there is pulse of people exiting, who aren’t hindered by those getting on, and vice versa. This means the train doesn’t ‘dwell’ in the station very long, meaning the route is quicker, and the chance of delay is less.

Underground systems also neatly illustrate why cash is the kryptonite of public transport. The transaction for your ride doesn’t occur on the platform, so it doesn’t hinder loading and unloading. It usually happens in a big entrance hall with a row of shiny gates (not so shiny in some systems), where people who have tickets already sail through at speed. Those who need to buy tickets are off to the side, and those who need to use a person to accomplish their sales transaction are usually marginalised further still. Thus, the tourist, or the infrequent user doesn’t hold up anybody else.

With trams, you usually buy your ticket from a machine on the street (e.g., Zurich, St Etienne, Geneva) or from a machine inside the tram in Lisbon (but not from the driver).

With buses on the other hand, cash fares almost always involve the driver, and the more cash fares there are, the longer the wait. What then, are some solutions for dealing with cash on buses.

Cardiff — don’t give change. Saves time, really screws you over if the smallest thing you have is a 20 pound note (so you won’t do it again).

Los Angeles — don’t give change. Saves time, but the US obsession with paper money means that you need to try to feed one of their super-ratty $1 bills into a note feeder, which can tak aaaaaggggges.

Umeå, Sweden — don’t take cash AT ALL. You either have a their bus pass card, or you have to use a credit card (no pin or signature required, just a swipe).

Dijon — use a round fare amount (1 euro), so that people don’t have to fiddle with extra coins. Travel cards accepted at all doors on the bus for faster loading.

Lisbon — make the electronic fares so cheap that even most tourists would have one. RFID card costs 50c. Fare with card 80c. Fare without card 1.40. Integrated ticketing for funiculars, trams, buses, and metro really make getting a card simple.

Now, let’s compare and contrast with Dunedin:

  • Cash accepted on bus (bonus points for time wasted with drivers sometimes grumbling over breaking of small notes) and fares requiring complicated change
  • RFID cards stupidly expensive ($5), compared to Lisbon card (50c, made of light card, easily replaceable)
  • RFID Go Card only gives measly discount (therefore, casual users unlikely to bother with high upfront cost and little discount)

The practical upshot of this is that if the buses are busier, it inevitably means each stop takes increasingly long as it is slow boarding people, and a busier bus becomes a victim of its own suggest.

Solutions for Dunedin:

  1. Get cheaper RFID cards (Lisbon’s cardboard ones work just fine).
  2. Create a real incentive to get a Go Card. Perhaps make a casual fare $3.00, or you can get a Go Card on the spot for $5, with $4.50 credit. This way, if you plan to take two bus trips, buying a Go Card is a no brainer.
  3. Make all the casual fares whole dollar values (simplifies change giving).

Longer term solutions:

  1. With the tap-and-go credit cards coming to NZ, enable these for use (and make them cheaper than cas).
  2. Get stronger RFID system, so that you don’t have to take your card out of your wallet/bag/purse
  3. Consider altering the zoning system, so that people with Go Card don’t need to interact with driver. In Lisbon, this is achieved by having no zoning. In Wellington, you tap your card as you get on AND as you exit, which then calculates zones travelled (if you don’t tap your card on exit, you get charged to the end of the route).


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Why primary school children shouldn’t do town planning.

It seems that fairly large tracts of Florida make for some amazing art, but it’s not town planning. More like doodling with patterns, and being, ‘Oh, that could be be a town layout’.

Some of them are beautiful. Some of them remind me of towns I’ve built with SimCity*

Really do click through. In addition to some of them being amazingly beautiful as a satellite image, and amazingly stupid as town planning fails, there are links to google maps and streetview, so you can explore these neighbourhoods, including the under-developed and overgrown ones.

*The difference between these grids and those that you might make in SimCity is if there is one thing that SimCity has taught me is the importance of good rail connections. Building roads just leads to congestion – quel surprise! Reinforced of course, by visiting places that actually have amazing public transport (Hi Lisbon! Hi Toulouse!).

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No surprises

The special votes have now been counted. The ODT sticks with a fairly First Past the Post frame, noting that the gap between Butler and Weatherall closed from 57 to 43 votes.

However, I’d maintain that that is not the most interesting part of the special votes, and Butler is not the person who could gain most from a re-count.

  • The special votes strongly favoured the young candidates. With postal voting, perhaps it is the influence of younger people overseas, but MacTavish and Hawkins each gained 28 first preference votes, followed by Thomson with another 22, Vandervis and Acklin with 17, Butcher and Clark on 14, then Butler with an extra 13.
  • The biggest change in the specials is at Hawkins’ elimination. He now loses out to Butler by 28 votes, whereas previously it had been 60. Unfortunately, because Butler was eliminated at the last step, it is not possible to tell where her votes would have been redistributed, or if it would have made a difference. One would assume that her supporters might not be casting their preferences for Weatherall and Hudson, however, but whether enough would have put Hawkins down as a later preference is anyone’s guess.

I’ve updated the graph, but it really is not very different from the last version (Click for larger version).

I’ve also zoomed in a bit on the final stretch, and you can really see the dog fight for the last few seats.

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Special Vote Predictions — DCC Central Ward & STV

Over the weekend, I did some analyses of the Dunedin City Council Central Ward election, which has produced a surprising amount of interest. The latest iteration of the graph (which isn’t really all that different to the earlier) is reproduced below. Having had some days to mull over it, I’m now prepared to make some predictions on what might happen with the special votes.

Nothing — mostly, I think with only 300 votes left to count that it is unlikely that the results will change.

Butler — There has been some suggestion that with Butler only 57 votes behind Weatherall, that she might catch him on specials. I agree with Janine Hayward that this is unlikely. This is because she would need a monstrous swing in the special votes (a reasonable number of which are likely to be invalid). Secondly, and quite importantly, as the last candidate to be excluded, all other unsuccessful candidates votes have already been redistributed, so there are not likely to be any further surprised from transferring votes. UNLESS, one of the currently deemed elected councillors is excluded, in which case their later preferences might give her the edge (see my next point).

Marlow v. Stevenson — To my mind, the biggest chance of change probably hinges around the point I’ve marked with (7) on the graph. Marlow is eliminated with 54 votes less than Stevenson (who goes on to be elected). Special votes can favour more conservative candidates (although sometimes also green candidates, as we’ve just seen with the Wellington mayoralty). If Marlow was to edge out Stevenson (and Marlow does quite well on the transfer at Dixon’s elimination), then I suspect Stevenson’s vote would transfer to younger/lefter/female candidates, which I suspect would boost Hawkins and Butcher. Most likely, Hawkins would then replace Stevenson as an elected councillor. As to Marlow, his elimination favours Hudson (who at that stage is quite far behind Weatherall), so that could be change there as well. Maybe. This whole scenario is very unlikely, however.

Notes to graph:

  1. Thomson and Vandervis exceed threshold to be elected on first preferences, so their ‘surplus’ vote is redistributed proportionately to their second preferences.
  2. On the exclusion of Gallagher, MacTavish (green line) receives a strong boost
  3. Staynes (brown line), receives a steady stream of later preferences, rising strongly as other candidates are excluded.
  4. When Hawkins is eliminated, MacTavish receives a large boost from his subsequent preferences.
  5. However, because MacTavish has already been elected, these votes then bolster Butcher and Stevenson.
  6. Despite polling strongly on first preferences, Butler receives disproportionately fewer late preferences, and is the last candidate to be excluded.

Other observations

On the whole, this really shows STV in action. There are several groups of candidates, who while not formally aligned, are clearly aligned in the minds of voters. The way that Gallagher and Hawkins (two young liberal men) boost liberal women (MacTavish, Stevenson, Butcher) on elimination reflect one aspect of Dunedin. And also the way that business-oriented men (Walls, Marlow) boost other business-oriented men (Staynes, Hudson, Weatherall) show the transfer in practice again.

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