Friday, March 18, 2011

The Not So Triumphant Return Of Poll Soup

I haven't provided a poll soup update since 2010, but with a campaign around the corner, it's worth checking in. Before we get to that, I must meet Blogging Council standards and issue the following disclaimer:

Warning - The following post contains graphic information and poll numbers that may not be suitable for some Liberals. Reader discretion is advised.

With that out of the way, let's recap the four March polls:

Ekos (Feb 24 to Mar 8, n = 2488 auto dial)

CPC 35%
Lib 28%
NDP 15%
Bloc 9%
Green 10%
Other 3%

Angus Reid (Mar 8 to Mar 9, n = 1021 online)

CPC 39%
Lib 23%
NDP 17%
Bloc 9%
Green 9%

Leger (Mar 7 to Mar 10, n = 2153 online)

CPC 36%
Lib 23%
NDP 18%
Bloc 10%
Green 10%
Other 3%

Ipsos (Mar 7 to Mar 9, n = 1002 phone)

CPC 40%
Lib 27%
NDP 16%
Bloc 11%
Green 5%

RUNNING AVERAGE (change since December in brackets)

CPC: 37.7% (+1.6%)
Lib: 25.8% (-2.7%)
NDP: 16.4% (+0.8%)
BQ: 9.7% (-0.1%)
Green: 8.1% (-0.4%)

As a programming note, the average above is based on all polls (not just those listed here), taking into account:
-sample size
-pollster accuracy (based on provincial and federal elections over the past 5 years)
-a 14 day half life (so a new poll is weighted twice as heavily as a 2-week old poll)

As the graph shows, we've definitely seen a widening of the Tory lead since January. To pinpoint it, I shrunk the poll halflife to 5 days and retroactively ran week-by-week averages:

As you can see, the gap really widens around early-to-mid February. Your guess is as good as mine as to the cause. The current theory I'm working on places most of the blame on Charlie Sheen.

So what does this all mean? Well, my seat projection formula gives the Tories an 85% chance at a majority, and projects the following seat ranges (at 95% confidence):

CPC: 148 to 178
LPC: 53 to 79
Bloc: 49 to 61
NDP: 17 to 31

Although the national vote numbers are largely in line with the last election result, the Tories get into majority territory because their support is up in Ontario (which means a dozen extra seats) and down in Quebec (which means a few less) and Alberta (which means zero less).

Now before anyone panics, keep in mind this is based on the polls we're seeing right now. Polls of a relatively unengaged electorate. The vote numbers will move during a campaign. The last three times the government changed in Canada, the party taking power trailed at the start of the campaign.



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