Look Ma, No Possum!

Well not quite, but I’m heading out to the boonies for a holiday so there will be less Possum over the next 2-3 weeks, depending on the joys of rural internet access.There will be updates once or twice a week.

Apologies for the slack comment responses over the last few days, I’ve been flat out but I’ll get to them in big wads over the holiday.

Pollycide Part 3 - The Verification.

Continuing on from Pollycide 1 where we used various weights derived from the quarterly Newspoll data to give us some experimental 2 party preferred results to show us the type of seats that would have likely changed hands in a July election, and following on from Pollycide 2 where we then used some linear programming to fit that seat pattern into the actual swings observed in the quarterly Newspoll – we now take it all back to basics, because sometimes the simple things in life are… well, simple and effective.

I noticed some dubious reaction to how these seat swings are possible (well, I noticed them once I managed to get past all the ALP supporters throwing confetti everywhere), so I thought we’d get back to the basics to show that I’m not making this up.

To do this, we’ll use the Newspoll quarterly data from March-June 2007, and compare that to the actual 2004 Election results to give us the TPP swings for each state. We can then compare these swings using the State Pendulums and we’ll get a basic, but realistic assessment of the seats that would have been likely to change hands were an election held in July.

To start off with, let’s take a squiz at the 2004 Election TPP results and the Q2 Newspoll data to find the state swings:

2004 Election	TOTAL	NSW	VIC	QLD	SA	WA
Coalition	52.8	51.2	51	57.1	54.4	55.4
ALP	47.2	48.8	49	42.9	45.6	44.6
2007Q2 Newspoll
Coalition	43	39	42	46	44	50
ALP	57	61	58	54	56	50
ALP Swing	9.8	12.2	9	11.1	10.4	5.4
Coalition Swing	-9.8	-12.2	-9	-11.1	-10.4	-5.4

That entry “ALP Swing” is the one you want to pay attention to here.

Now comparing these swings to these graphs we get the following numbers of seats changing hand for each state:

NSW: ALP gain of 17

Vic: ALP gain of 8

Qld: ALP gain of 14

SA: ALP gain of 5

WA: ALP gain of 2.

That’s a total gain of 46 seats.

However, lets look at Tassie and the NT where Solomon would fall with a 2.9% swing, Bass would fall with a 2.7% swing and Braddon would fall with a 1.2% swing.

With a national swing of 9.8% - it’s a safe bet that those three seats would all fall as well, giving us a total ALP gain of 49 seats.

The Pollycide 2 numbers and the seat list suggested 47 seats would have been lost in NSW, Vic, Qld, SA and WA. Remember, that seat list was derived from Pollycide 1, and adjusted to fit within the State based swings – although it was more luck than skill that the numbers matched up just about perfectly as it could have been 3 or 4 seats in either direction due to the nature of the maths and where I chose to draw the line in terms of leaving some unaccounted for swing in NSW.

So, from Pollycide Part 1 we can see the types of seats that would have been lost in a July election, from Pollycide Part 2 can see a good estimation of which seats and the margins involved were an election held in July, and with Pollycide 3 we have verified those numbers.

That’s the good news for the government. Yes, the GOOD news.

The bad news is that the above verification based on the state Newspoll swing estimations doesn’t account for the composition of marginal and safe seats. The ALP are only swinging 4.1% toward them in their safe seats, the marginals are swinging 9.3% toward the ALP and the safe government seats are swinging 14.6% toward the ALP for an overall national swing of 9.8%.

As there was residual swing left from the seat calculations in Pollycide 2 (which is where we tried to account for the marginal and safe seat movements), that means that the swings actually underestimate the actual seat numbers that would have been lost.

By how much? – up to 10-15 seats depending on where the residual swing fell.

So what we can feel fairly safe saying is that were an election held recently, according to 3 months worth of polling by Newspoll, the ALP would have gained 49 seats as a minimum, somewhere around 55-60 seats as a more likely possibility and a high of somewhere around 65.

That really is a Pollycide.

If you want to check out the details of any of the seats mentioned in the Pollycide series, Adam Carrs magnificent psephology site has a smorgasbord of info on all of them in his 2007 Federal Election Guide.

Small Update - I over counted NSW by 1 as a result of putting a seat in the wrong spot in my NSW swing graph.Its all fixed up now with NSW giving 17 seats rather than 18.

Thanks to the dozen or so people that pointed it out - nothing get’s past you folks.

Swings for Seats - National and State graphs

I’ve broken the Mackerras Pendulum down into national and state based swing graphs.The way to read them is like before, choose a swing on the vertical axis, trace it across until it hits the swing line, and then trace down to the horizontal axis to find the seats that the ALP would win or lose given that swing.

These are thumbnails so just click on them to blow them up to full size.

National Swing NSW Swing Qld Swing

Victorian Swing WA Swing SA Swing

For the remaining 9 seats in Tassie, NT and the ACT, I’ll give them as a table.

It shows the seat, the party that currently holds it, the State/Territory the seat is in and the swing needed for the ALP to win or lose it e.g a positive number represents the swing toward they ALP they need to take the seat, a negative number represents the swing away from the ALP they need to lose the seat.

Seat	Party	State	ALP Swing
Solomon	Lib	NT	2.9
Bass	Lib	Tas	2.7
Braddon	Lib	Tas	1.2
Lyons	ALP	Tas	-3.7
Franklin	ALP	Tas	-7.6
Lingiari	ALP	NT	-7.7
Canberra	ALP	ACT	-10.1
Denison	ALP	Tas	-13.3
Fraser	ALP	ACT	-13.4

UPDATE:

The outstanding Simon Jackman has up a lovely graph with state by state swings and the seats involved.And it looks good too!

http://jackman.stanford.edu/blog/?p=281

Possum Feeders Alert

This is for those folks that read the site by feeds.The two last articles Pollycide Part 1 and 2 have been rewritten to more accurately reflect what I was doing and what it means and how it all works.

For those reading this via a browser…

Move on, nothing to see here

Pollycide 2 – Draft Numbers

This article has been rewritten as well to hook more coherently into Part 1.

OK folks, we have the first draft of the numbers on the trends we highlighted earlier in Pollycide Part 1. If you haven’t read it, I suggest you do.

The way these were calculated was kind of complicated but used a type of linear programming, which is basically where glorious software figures out the value X (the size of the swing in each seat cohort) under the constraints of A, B, C etc, or in our case the various swings and proportions which make the numbers balance out to reflect the Newspoll data.

The table contains the seat, then the state, then the nominal TPP from the 2006 redistribution followed by the estimated ALP and Coalition TPP figures.These are all currently Coalition held seats.

 

Seat	State	2006 Redistribution			ALP Est	Coalition Est
		ALP TPP	Coal TPP
Macquarie	NSW	50.5	49.5		61.83	38.17
Wakefield	SA	49.3	50.7		59.24	40.76
Kingston	SA	49.9	50.1		59.01	40.99
Bonner	QLD	49.4	50.6		58.74	41.26
Makin	SA	49	51		58.11	41.89
Eden-Monaro	NSW	46.7	53.3		57.22	42.78
Wentworth	NSW	47.4	52.6		57.09	42.91
Lindsay	NSW	47.1	52.9		56.79	43.21
Moreton	QLD	47.2	52.8		56.54	43.46
Blair	QLD	44.3	55.7		56.11	43.89
Herbert	QLD	43.9	56.1		55.71	44.29
Bennelong	NSW	46	54		55.69	44.31
Hasluck	WA	48.1	51.9		55.62	44.38
Cowper	NSW	43.4	56.6		55.56	44.44
Stirling	WA	47.9	52.1		55.42	44.58
Longman	QLD	43.4	56.6		55.21	44.79
Page	NSW	44.5	55.5		55.02	44.98
Dobell	NSW	45.2	54.8		54.89	45.11
Sturt	SA	43.2	56.8		54.78	45.22
McEwen	VIC	43.5	56.5		54.64	45.36
Paterson	NSW	43.2	56.8		54.53	45.47
McMillan	VIC	45	55		54.50	45.50
Robertson	NSW	43.1	56.9		54.43	45.57
Corangamite	VIC	44.6	55.4		54.10	45.90
Petrie	QLD	42.1	57.9		53.91	46.09
Boothby	SA	44.6	55.4		53.71	46.29
Deakin	VIC	45	55		53.67	46.33
Kalgoorlie	WA	43.6	56.4		53.59	46.41
Gippsland	VIC	42.2	57.8		53.34	46.66
La Trobe	VIC	44.1	55.9		52.77	47.23
Dickson	QLD	40.9	59.1		52.71	47.29
Gilmore	NSW	40.5	59.5		52.66	47.34
Hughes	NSW	41.2	58.8		52.53	47.47
FLYNN	QLD	42.2	57.8		52.37	47.63
Bowman	QLD	41.1	58.9		52.08	47.92
Dawson	QLD	39.8	60.2		51.61	48.39
Higgins	VIC	41.2	58.8		51.51	48.49
Leichhardt	QLD	39.7	60.3		51.51	48.49
Hinkler	QLD	41.2	58.8		51.37	48.63
North Sydney	NSW	39.9	60.1		51.23	48.77
Dunkley	VIC	40.6	59.4		50.91	49.09
Kooyong	VIC	40.4	59.6		50.71	49.29
Ryan	QLD	39.5	60.5		50.48	49.52
Canning	WA	40.4	59.6		50.39	49.61
Macarthur	NSW	38.9	61.1		50.23	49.77
Goldstein	VIC	39.9	60.1		50.21	49.79
Warringah	NSW	38.7	61.3		50.03	49.97
Flinders	VIC	38.8	61.2		49.94	50.06
Menzies	VIC	39.3	60.7		49.61	50.39
Wide Bay	QLD	37.8	62.2		49.61	50.39
Forrest	WA	39.5	60.5		49.49	50.51
Hume	NSW	37.1	62.9		49.26	50.74
Casey	VIC	38.6	61.4		48.91	51.09
Forde	QLD	37	63		48.81	51.19
Fisher	QLD	37	63		48.81	51.19
Wannon	VIC	37.6	62.4		48.74	51.26
Greenway	NSW	39	61		48.69	51.31
Fairfax	QLD	36.7	63.3		48.51	51.49
Moore	WA	39.1	60.9		48.26	51.74
Berowra	NSW	36.9	63.1		48.23	51.77
Lyne	NSW	35.9	64.1		48.06	51.94

This is one alternative of what could explain the swings from quite a large number of mathematical possibilities, but it is the one probably closest to the ‘median possibility’ (which is not a particularly technical term BTW, but literal) , in that the others contained quite large swings in some seat cohorts and produced some pretty funny results.

That’s 47 seats falling in July according to the quarterly Newspoll data analysed to within an inch of its life, and we still have around a 2% swing to the ALP to allocate in NSW that can’t be extracted properly from the data without producing some silly things, as well as an extra 3% or so swing to the ALP in the government safe seats. Those two probably are a bit of a twin act in NSW somewhere, but the latter could well be spread around.

This is something approaching the most likely result of an election were it held in July based singularly on uniform swings by state, city type and safe/marginal grouping that is consistent with the Newspoll data. However, with a 2% swing to the ALP not really accounted for, there would have been some reallocation of the size of the vote in some of those seats, possibly including the loss of an extra 10-15 seats as a worse case scenario for the government, depending on where that extra swing went.

This is a little better for the Coalition than I had expected from the initial play around with the data in Pollycide Part 1, but only just. You might notice that the ALP TPP has calmed down a fair bit from the earlier post that used the Experimental TPP– that’s the result of removing as much feedback from the combined swing issues as was possible, but you also might notice that the seats, or rather the types of seats identified in Pollycide Part 1 as being in danger was actually pretty close to the mark.

That gigantic 14.6% swing happening in the safe government seats is the real, profound danger for the Coalition. I can’t remember anything like this happening before (maybe the living electoral encyclopaedia Adam could tell us) and only local factors would have saved the Coalition any marginals were an election held in July.

The other big killer is the fact that the safe ALP seats have only swung 4.1%.It’s not unusual for largish swings to happen, but in the wrong seats such as the ALP experienced in the 1998 election.

This, however, is a completely different ballgame. The swings are in all the right places for the ALP and all the wrong ones for the Coalition. It’s leading me to believe that if the polling behaviour holds, the ALP will win more seats, a lot more seats than their national swing would ordinarily suggest.

 

So the question becomes, if there are big swings happening in unusual places, which there must be for the Newspoll data to be right (which it surely would be - who doesnt worship the truthly godliness of the Newspoll? ) where are they?

Anyone on the ground in safe government seats, particularly in NSW and Qld that are picking up an anti-government vibe worth around, oh….. say, 14.6% ?

Continue on to Part 3 - The Verification

 

 

 

 

Pollycide Part 1

I’ve completely rewritten this article to make it more coherent and reflective of what I was trying to say rather than making it look like the government was going to be nailed with a 70 seat loss. Yesterdays attempt was appalling gibberish that confused everyone including myself.So if you’ve read this before - it’s now all new and improved!

If you havent, welcome aboard to a long argument

As many of you know, the ALP primary vote projections based on the combination of the recent quarterly demographic and Marginal/Safe seat Newspolls showed what can only be described as horrific results for the Coalition.

Well let me say from the outset, what you are about to witness cannot be described as anything other than absolute devastation. Coalition supporters might want to remove any sharp objects from their vicinity before reading on.

The previous projections were rough, they didn’t take into account the redistributions since the last election, and they didn’t take into account capital vs. non capital breakdowns which is really, really important in some States. But most importantly, as I stated at the beginning of that article, it didn’t include the most recent quarterly Newspoll because, frankly, I didn’t believe it’s contents. Not that it was wrong, but just that I COULD NOT BELIEVE what it was saying and what I was seeing.

You see, the data from the last quarterly Newspoll is even worse for the Coalition than the Q1 Newspoll. Much, much worse as the results in the states with the most Coalition seats, like NSW, tanked in the last quarter whereas the ground the Coalition made up were in States like WA ands SA where the seats they hold are relatively few.

This is the real danger that these latest Newspoll numbers hint at.

What we are going to do is create a set of weighted ratios out of that quarterly Newspoll data and apply them to Coalition seats – not to tell us what the vote necessarily is in those seats, but to highlight the Coalition seats that are in danger because of the way the vote is swinging.

To start with, we’ll use a breakdown of the redistributed two party preferred results since the last election based on the Mackerras Pendulum for the initial redistribution, and make experimental TPP projections and swing projections based on the last quarterly Newspoll, March to July 2007 including State, Capital City vs. Non Capital City and Marginal vs Safe swings.

I took the State based Newspoll figures and determined the TPP swing for the ALP since the last election by State. I then took the national TPP swing for the ALP since the last election from that same Newspoll.

I then divided each State swing by the national swing to give me a state weight. Let’s use NSW as an example. The NSW swing to the ALP was 12.2, and the national swing was 9.8.The state swing divided by the national swing is 1.245.

That means in NSW the swing towards the ALP is 1.245 times the national swing.

I then took the national capital city swing towards the ALP (9.5) and divided it by the national swing (9. to give me a capital city weight of 0.969.This means that the capital cities are swinging 0.969 times the national swing. I repeated this process for the non-capital cities to arrive at a non-capital city weight of 1.245 (Yes it is the same as the NSW State weight as both had a TPP swing to the ALP of 12.2).

Next I took the national marginal seat TPP swing to the ALP (9.3) and divided it by the national swing (9. to get a marginal seat weight of 0.949.I repeated this process to get a safe government seat weight of 1.4898. That, by the way, is huge.

To get an idea of how these weights stack up on a seat by seat basis is simple and best explained with an example. Let’s take the NSW seat of Bennelong (every psephs favourite seat)

At the 2004 election the TPP result was 54.33% Coalition and 45.67% ALP.

The effect of the 2006 redistribution on Bennelong was to reduce that TPP down to a notional Coalition 54% and ALP 46%.

Bennelong is a NSW, capital city, marginal seat. Hence, the estimated TPP vote for Bennelong based on the Newspoll quarterly breakdown, using the weights described above is:

Estimated Bennelong TPP for the ALP = Redistributed ALP TPP + (state weight * capital city weight * marginal seat weight * national swing).

Hence, the estimated ALP TPP for Bennelong = 46 +(1.245 * 0.969 * 0.949 *9.

= 46 + 11.22

= 57.22

These are the ALP swings and the ALP swing weights as determined by the Newspoll data for the March-July 2007 results.

The National Swing is 9.8

NSW, swing 12.2, weight 1.245

Vic , swing 9, weight 0.918

Qld, swing 11.1, weight 1.133

SA , swing 10.4, weight 1.061

WA, swing 5.4, weight 0.55

Marginal Seat swing = 9.3 weight = 0.949

Safe Government Seat swing = 14.6 weight = 1.490

Capital City swing = 9.5 weight = 0.969

Non Capital City swing = 12.2 weight = 1.245

However, we have a problem. There will be feedback between some of the weights, for instance if there is a large swing in non-capital city NSW, that will inflate both the non-capital city ALP swing AND the NSW ALP swing AND most likely the swing against the government safe seats. If we apply that weighted swing to most seats it will produce an inflated TPP result.

But it’s also a good thing.

The feedback built into the weights also allows us to identify the seats that are most likely to be suffering swings against them simply because of where those big swings broadly identified by Newspoll are occurring.

For instance, we know NSW has a 12.2% swing to the ALP, we know that there is a swing against the government of 14.6% in their safe seats and we know that non-capital city seats are swinging slightly more than capital city seats. So its probably a fair assumption to make that there are a number of NSW non capital city seats, that are considered safe government seats and which are experiencing very large swings.

What the following table attempts to do is to identify those seats by using an experimental, weighted TPP projection and a nominal swing projection for each seat derived from that TPP. These are based on the 2006 redistribution as the underlying, pre-existing TPP vote for the last election.All seats are nominally (as in post 2006 redistribution) Coalition held seats.

 

Seat	State	ALP TPP		Experimental ALP	Experimental ALP
		2006 Redistribution		TPP	Swing
Cowper	NSW	43.4		66	22.6
Paterson	NSW	43.2		65.8	22.6
Gilmore	NSW	40.5		63.1	22.6
Hume	NSW	37.1		59.7	22.6
Lyne	NSW	35.9		58.5	22.6
Farrer	NSW	34.6		57.2	22.6
Parkes	NSW	31.2		53.8	22.6
Riverina	NSW	29.3		51.9	22.6
Blair	QLD	44.3		64.9	20.6
Herbert	QLD	43.9		64.5	20.6
Longman	QLD	43.4		64	20.6
FLYNN	QLD	42.2		62.8	20.6
Petrie	QLD	42.1		62.7	20.6
Dickson	QLD	40.9		61.5	20.6
Dawson	QLD	39.8		60.4	20.6
Leichhardt	QLD	39.7		60.3	20.6
Wide Bay	QLD	37.8		58.4	20.6
Fisher	QLD	37		57.6	20.6
Forde	QLD	37		57.6	20.6
Fairfax	QLD	36.7		57.3	20.6
McPherson	QLD	36		56.6	20.6
Fadden	QLD	34.7		55.3	20.6
Groom	QLD	31		51.6	20.6
Moncrieff	QLD	30.1		50.7	20.6
Maranoa	QLD	29		49.6	20.6
Mayo	SA	36.4		55.7	19.3
Grey	SA	36.1		55.4	19.3
Barker	SA	30.1		49.4	19.3
Macquarie	NSW	50.5		68.1	17.6
Robertson	NSW	43.1		60.7	17.6
Hughes	NSW	41.2		58.8	17.6
North Sydney	NSW	39.9		57.5	17.6
Macarthur	NSW	38.9		56.5	17.6
Warringah	NSW	38.7		56.3	17.6
Berowra	NSW	36.9		54.5	17.6
Cook	NSW	36.3		53.9	17.6
Mackellar	NSW	34.5		52.1	17.6
Bradfield	NSW	32.5		50.1	17.6
Mitchell	NSW	29.3		46.9	17.6
McEwen	VIC	43.5		60.2	16.7
Gippsland	VIC	42.2		58.9	16.7
Flinders	VIC	38.8		55.5	16.7
Wannon	VIC	37.6		54.3	16.7
Indi	VIC	33.7		50.4	16.7
Murray	VIC	25.9		42.6	16.7
Mallee	VIC	25.2		41.9	16.7
Bowman	QLD	41.1		57.1	16
Ryan	QLD	39.5		55.5	16
Sturt	SA	43.2		58.2	15
Eden-Monaro	NSW	46.7		61.1	14.4
Page	NSW	44.5		58.9	14.4
Hinkler	QLD	41.2		54.3	13.1
Higgins	VIC	41.2		54.2	13
Dunkley	VIC	40.6		53.6	13
Kooyong	VIC	40.4		53.4	13
Goldstein	VIC	39.9		52.9	13
Menzies	VIC	39.3		52.3	13
Casey	VIC	38.6		51.6	13
Aston	VIC	36.8		49.8	13
Wakefield	SA	49.3		61.6	12.3
Wentworth	NSW	47.4		58.6	11.2
Lindsay	NSW	47.1		58.3	11.2
Bennelong	NSW	46		57.2	11.2
Dobell	NSW	45.2		56.4	11.2
Greenway	NSW	39		50.2	11.2
McMillan	VIC	45		55.6	10.6
Corangamite	VIC	44.6		55.2	10.6
Bonner	QLD	49.4		59.6	10.2
Moreton	QLD	47.2		57.4	10.2
Kalgoorlie	WA	43.6		53.6	10
Canning	WA	40.4		50.4	10
Forrest	WA	39.5		49.5	10
Pearce	WA	37		47	10
O’Connor	WA	29.6		39.6	10
Kingston	SA	49.9		59.5	9.6
Makin	SA	49		58.6	9.6
Boothby	SA	44.6		54.2	9.6
Deakin	VIC	45		53.3	8.3
La Trobe	VIC	44.1		52.4	8.3
Moore	WA	39.1		46.9	7.8
Tangney	WA	38.2		46	7.8
Curtin	WA	35.3		43.1	7.8
Hasluck	WA	48.1		53.1	5
Stirling	WA	47.9		52.9	5

Please note, this too is rough, and could be cleaned up even further with more time and more data. But that clean up process wouldn’t dramatically alter the nature of what is going on.

What the above table tells us is that the seats with the highest experimental swing are the best candidates to actually be experiencing swings against them that are necessary to balance out the Newspoll data.

The problem for the government comes from the 14.6% swing against their safe seats being an average swing. Now clearly some coalition safe seats wont be swinging much at all, which makes other safe coalition seats having larger than 14.6% swings against them to balance out the numbers. Some probably having much larger swings against them.

For the Newspoll figures to be right means that a lot of these seats will have fallen if an election were held in July. They wouldn’t have fallen with those margins (because, remember they are inflated), but still would have gone.I’ll put some more realistic numbers to these swings in Part 2.

The danger for the government here is if the swing against their safe seats is uniform. The more uniform it is, the most seats they will lose.The government holds 49 seats that are considered safe (i.e. are held with a buffer of more than 6%) but are held with a margin of less than this 14.6% swing against them.

This is why uniformity in this swing would wipe them out. When I was playing around with this a few days ago, I couldn’t believe what I was seeing – we all talk about elections being won or lost in the marginals, but if the polls hold, the marginals will be irrelevant. Not that the Coalition is doing particularly well in that area either, with a 9.3% swing against them there.

And nor can they be satisfied of the usual saviour of anti-government swings – the swings in the opposition safe seats. The ALP is only picking up an average of a 4.1% swing in their own safe seats. That too is extremely surprising.

In part 2, I’ll use some linear programming (or what the more pure end of mathematics calls matrix algebra) to whittle down the size of these swings to be consistent with the national, state, capital city vs. non capital city and safe vs. marginal seats swings.Then we might get a better idea of how an election may have looked like were it held in July.

One thing is clear however, these results are catastrophic for the government, suggesting that only a handful of seats are truly safe and that there will be massive swings against them in many seats they thought were untouchable. That simply has to be the case for the size of the swings to balance out.

 

CONTINUE on to Part 2 where some realistic numbers are produced to reflect the actual swings

What’s a swing worth?

Just a quick nifty little graph today based on the Mackerras Pendulum.Click on it to blow it up.

What it shows is how many seats the ALP would win or lose at the election for a given uniform swing.

The way to read the graph is simple, pick a swing on the left hand side, trace it across until it intersects the red line, then move down to the bottom axis to see how many seats the ALP would win or lose based on that swing.

For example, if the ALP had a swing against it of 1%, which would be a -1% swing, they would lose 4 seats.

If the ALP had a swing toward it of just over +2%, it would gain 8 seats, and a +5% swing would gain them 19 seats.

Play it, Sam. Play ‘As Polls Goes By’.

Yes, it’s another poll and another cheesy movie headline, but this time it’s best summed up by the famous misquote of this line from Casablanca:

“Play it again Sam”.

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