Sunday, April 10, 2011

Swing Riding Close-Up:: Edmonton—Strathcona

Linda Duncan, NDP MP Edmonton—Strathcona, Edmonton Journal
I've been looking at election data the past week and have been creating maps based on prior election data. Edmonton—Strathcona is a black eye {or spec of orange [pdf]} to the Conservatives in a sea of blue. The riding evokes Austin, a liberal enclave in the hill country of Texas. Cyberpresse has great maps of the 2008 election, at the polling station level::

click on image to open interactive federal 2008 election results map feature on Cyberpresse,
use pull-down menu to choose Federal riding
This recent Globe & Mail article on the riding helps to flesh out the story the 2008 map is telling. The western portion of the riding is the heart of the NDP territory with Whyte Avenue as its main street. The riding has a high turnout, reportedly the highest in the province at 65.4% in 2008. Here's a graph of turnout by votes by party for the 2008 election::

This shows no real differential effect for party. In some of my other maps, I found party effects that were present in 2008, but not 2006. I created a turnout map for 2008::

Last Saturday, I introduced a draught of the "Swingdex" for Ontario federal ridings, which attempts to determine a riding or polling district's partisanship. I'm still refining the formula and plan on using cluster analyses to better capture differences along the scale that, ideally, had strong predictive ability. The formula is based loosely on the Cook PVI. The following two maps only look at a polling district in relation to others in Edmonton—Strathcona. I did one with the NDP index and one with the Conservative index. The numbers are the polling district's percentages above or below the party's average in 2006 and 2008 for the entire riding. So, a +2NDP means that the polling district was 2 percentage points above the NDP 2006 and 2008 riding average of 38%. Given the very close two-way race between Linda and Rahim Jaffer, the maps will be an inverse of each other. Note that the metrics are different, so the colour codings and categories have different index {percentage} ranges.

Conservative Index {Swingdex} for Edmonton—Strathcona

NDP Index {Swingdex} for Edmonton—Strathcona 
Not surprisingly, there's a core of NDP support with hot clusters. The Conservative votes tend towards the outer suburban areas. The districts along Whitemud Drive on the southwest corner of the riding were close and have lower turnout, so I'm sure the NDP will be targeting there. These maps illuminate more than what meets the eye on the overall winner maps {the Cyperpresse example above}. While several neighbourhoods went for Jaffer in the middle of the map by sizeable margins, there were plenty of NDP votes received there, as well. It points out to many districts that the Conservatives need to address throughout the riding.

Twitterversion:: [blog+maps] Swing Riding Close-Up:: Examination of Edmonton — Strathcona, #NDP orange in a sea of Alberta blue  @Prof_K

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