Sunday, 23 February 2014

A quick look at the other tools

After this weekend there will be two more before election day. Last weekend we covered the maps of electoral trends, which leaves us with the seat run-downs and pendulum to discuss. It might seem like a good idea to dedicate this weekend to one, next weekend to the other and the final weekend to formalising predictions. However, next weekend I will be providing summaries of each Legislative Council party. While this is not useful in regards to predicting electoral outcomes I personally believe it is one of the most important subjects I cover on this blog since it helps people make informed above- or below-the-line votes, provides links to each parties website and just generally makes the whole process easier. I know I had a few of my non-regular readers visit my blog exclusively for those summaries.

The Polls and the Pendulum

This week, then, we will cover both the seat rundowns and the pendulum. For the latter we will be using Antony Green'sdata as opposed to the numbers produced by the South Australian Electoral Districts Boundaries Commission. You can read the important distinctions at the previous link, but basically Antony Green's data is for psephological purposes while the EDBC's is for the redistribution of boundaries and factors in all kinds of demographic shifts. As Mr Green himself explains, “when calculating swing, you should be comparing with the 2010 election, not a mythical estimate of what the 2010 result might have been in 2014.”

Notice that the above pendulum is sorted alphabetically instead of by margin or party? You won't see a pendulum like that from anyone who actually knows what they are doing. Here, however, it is useful because we can directly cross reference the pendulum seat-by-seat with our other tools. However, for the purists or those more visually inclined, here is the same information of a Liberal-Labor scale.

Note that the Independents in Fisher, Frome and Mount Gambier are listed as Liberals

The Independents have been included with the Liberals on this scale for several reasons. Firstly, their margins are all measured against the Libs, so the Labor party is well down in a 3-horse race. Secondly, the Independents are conservative, suggesting that a lot of their votes would flow to the Libs if they did not run. This means that the Labor vote in these seats is not necessarily low because would-be Labor voters were seduced by the lure of an Independent (although it is a fair be that a lot of the Labor vote flowed to the Independents rather than the Libs and probably cost the Coalition the seat. Thirdly, in a hung parliament, it is expected the Independents would side with the Liberal Party to form government.

Although the Labor Party has more seats (and hence is currently in power), the Liberals fewer marginal seats: 3 (and an Independent) compared with Labor's 11. The Liberals only have one fairly safe seat (and an Independent) compared to Labor's 4, and while Labor has 11 safe seats the Liberals have 10, plus 1 Independent and 4 in the very safe category which Labor failed to reach. If the Liberals won all of Labor's marginals, they would hold 29 seats with 3 Independents by their side; if Labor won all of the Liberal marginals they would hold 29 seats with 3 Independents against them.

Assuming a uniform swing and support from the Independents, the Liberals need a 0.6% swing in their favour (which, if repeated in the Independent contest in Mount Gambier would also win them that seat. Even without the support of the greys, Steven Marshall would form a government on the back of a uniform 2.6% swing. Whether or not they will get this swing, of course, remains to be seen.

Seat Statistics

Swings, of course, are not uniform, although the search for a reliable indicator of where they will be stronger or weaker continues to allude me. Instead we are going to have to rely on seats being “Labor seats” and “Liberal seats” to calculate which seats are most open to being targeted. Previous analysis indicates that a seat that has a large swing one election might have a small swing the next, so such definitions can only be a rough guide at best.

Previously for the run downs I interpreted each seat on two factors – how strongly it supported a party (its “strength”) and how reliable that support was (its “volatility”). The former was subjectively assigned as very safe, safe or leaning, while the latter was intuitively divided into stable, variable and volatile. These assignments were based on the incumbency and margin (provided above in the pendulum) and the seat's history outlined last weekend. One additional factor used in the federal election – the state seats that lie within the federal seats – cannot be replicated at the state level.

This election we are going to try something different. For the purposes of making the results repeatable, consistent and measurable, these run downs will rely on more rigid definitions.

The VDTAs are useful for examining recent voting trends. The run downs attempt to identify long-term biases in seats. For this reason, historical inclination will be determined from the number of times a party has won the seat but lost the election – that is, where the seat's preferences are revealed to be skewed to one party or another relative to the state as a whole.

To do this, we first need to know the results of every election since 1938:

The following districts voted against the general trend in the following years:

From this we can calculate the following tables:

For simplicity we have ignored Independents. The contrary count is the number of times the seat has been won by a party that lost the election. Adelaide has voted for the ALP 11 times when the Coalition has gone on to win the election, which initially suggests this is a decent seat for Labor.

The In Step table shows how many times the seat has been won by the party that also won the election. This is useful because it lets us total the number of times a party has won the seat; realising that Playford has voted for the ALP 4 times in Coalition victories is somewhat meaningless until we also realise it has never voted for the Coalition.

The final table is calculated to show the percentage of times the ALP has won Coalition elections and vice versa. In Adelaide, Labor won the seat in 11 of the 12 Coalition-won elections (91.7%) and the Coalition won Adelaide in 3 of the 10 Labor elections (30%) since 1938. ALP data fro Little Para cannot be calculated because it has never participated in a Coalition-won election. No figures for Mount Gambier can be calculated since it has always elected an Independent.

Let's calculate the liability of each seat to favour a given party from the difference between these last figures. To continue to use Adelaide as an example, lets say the seat is 91.7 – 30 = 61.7% leaning to the ALP. Like most of the dramatic ALP leans, this is mostly historical, with a large opposition to the Coalition dominance prior to 1965 under the Playford-favouring Gerrymander creatively known as the Playmander. However lets leave the concerns about recent vs ancient trends to be picked up by the VDTAs and use this (admittedly arbitrarily calculated) figure for a ballpark and see what we can kick around.

I have also arbitrarily assigned leans of more than 66.66% the label “steadfast”, those over 33.33% “Reliable” and the rest “Leaning” (with the two previously mentioned exceptions of Little Para and Mount Gambier). This was not done simply because dividing the range into three equal-sized divisions is appealing. I subjectively assigned the labels to the seats and checked their values later. These values are close approximations of my intuitive divisions of the seats:

Adelaide: Reliable Labor
Ashford: Steadfast Labor
Bragg: Steadfast Liberal
Bright: Reliable Liberal
Chaffey: Reliable Liberal
Cheltenham: Steadfast Labor
Colton: Leaning Labor
Croydon: Steadfast Labor
Davenport: Steadfast Liberal
Dunstan: Reliable Labor
Elder: Reliable Labor
Enfield: Steadfast Labor
Finniss: Steadfast Liberal
Fisher: Steadfast Liberal
Flinders: Steadfast Liberal
Florey: Steadfast Labor
Frome: Leaning Liberal
Giles: Steadfast Labor
Goyder: Steadfast Liberal
Hammond: Steadfast Liberal
Hartley: Leaning Labor
Heysen: Steadfast Liberal
Kaurna: Reliable Labor
Kavel: Steadfast Liberal
Lee: Reliable Labor
Light: Steadfast Liberal
Little Para: Unknown
MacKillop: Steadfast Liberal
Mawson: Leaning Labor
Mitchell: Steadfast Labor
Morialta: Reliable Liberal
Morphett: Steadfast Liberal
Mount Gambier: Unknown
Napier: Steadfast Labor
Newland: Leaning Liberal
Playford: Steadfast Labor
Port Adelaide: Steadfast Labor
Ramsay: Steadfast Labor
Reynell: Reliable Labor
Schubert: Steadfast Liberal
Stuart: Steadfast Liberal
Taylor: Steadfast Labor
Torrens: Reliable Labor
Unley: Leaning Labor
Waite: Steadfast Liberal
West Torrens: Steadfast Labor
Wright: Reliable Labor

Exactly how this factors into the final results will have to wait until the predictions, but here is a quick look at the data:

On face value it looks as though the ALP has the slight majority in an even battle, but the Coalition only needs to break into the Labor Leaning seats to take a majority. Colton, Hartley, Mawson and Unley are seats to watch. Particularly Unley – a recurring oddball.

By and large this data conforms with the current state of the seats, which suggests a decent predictive power. Ignoring the unknowns (Little Para is Labor while Mount Gambier is Independent) and the Liberal-leaning Independents (Frome and Fisher are still listed as Liberal seats), there are only 3 seats from each party that have a supposed bias contrary to their current incumbent – Adelaide, Dunstan and Unley are currently Liberal while Bright, Light and Newland are currently Labor. These, again, will be worth watching. Again, particularly Unley.

Finally their historical inclination calculated here also closely correlate with the VDTA. All of the clear Liberal or Labor seats on the VDTA correspond with Liberal or Labor seats from today's data, with the single exception of the oddball Unley (again!) which is historically safe Liberal on the VDTA but leaning Labor here.

Fisher is slightly closer to grey than the other blue seats, but is still Liberal by both measures. The VDTA's slightly red Morialta is listed as reliable Liberal here, but the colour is so close to the midrange on the map I don't see this as a major disagreement. The other mid-ranged seats on the VDTA are as follows:

Hartley and Mawson – leaning Labor
Newland – leaning Liberal
Bright – Reliable Liberal
Light – Steadfast Liberal

Note that these last three – Bright, Light and Newland – are the three peculiarities listed above as Labor occupied but (by this post's reckoning) Liberal inclined. Either today's analysis has failed to capture a recent development in these seats, or the atypical Labor incumbency has biased the VDTA. All have passed to Labor for the last two elections after at least 4 wins by the Coalition, which could support either interpretation.

Either way, in the wider view, all of our methods are starting to align nicely.

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