Saturday, May 11, 2013

British Columbia's Election

B.C.'s election is drawing to a close and in TC's view it will be a comfortable majority for the NDP and Adrian Dix. Despite all the excitement about a Liberal comeback, the shift in the polls from big NDP leads in the early going to an apparently closer race now looks like a reversion to the mean: in other words we are seeing a return to something closer to the longer run average of political support for the two major parties in BC politics. Most polls except for a Forum Poll conducted on May 8 can be found here on the Tyee's Election Hook website.

There is little doubt the early polls captured something.  However, most of the movement appears to have been disaffected BC Liberal voters returning home, voters who were anti-NDP to begin with but undecided due to antipathy to the Clark government. The Liberal party's attacks on the NDP paid dividends here.  However, almost every poll has had the NDP above 40 per cent and the BC Liberals below (the two exceptions to this are both Forum polls).  The average of the polls conducted this week is:

BC Liberal - 37.2%
NDP - 43%
Green - 10.2%
BC Conservatives - 6.6%

TC expects to see about 50 New Democrats and about 35 BC Liberals win, possibly one Green although that is probably getting less likely.  Perceptions of a close race will drive some voters, who view both the Greens and the NDP favourably, towards the NDP in order to avoid re-electing the BC Liberals to a fourth term.

One or two points about the polling.  Forum research commits a sin that I think needs to be noted: they conduct their polls on a single day.  Their polling is conducted using Interactive Voice Response, a valid methodology where respondents answer a short phone survey where the questions are played back from a computer and the responses digitally recorded by punching phone keys. However, it means they can turn on their computers and just let them run until they have the sample they need (all firms weight their samples so that they resemble the population at large). In TC's view they should spread out the survey over a few days the way other firms do.

Consider Forum's description of its methodology of its April 30th poll:
The Forum Poll™ was conducted by Forum Research with the results based on an interactive voice response telephone survey of 1,055 randomly selected residents of British Columbia 18 years of age and older. The poll was conducted on April 30th, 2013.
Now compare that to an American IVR polling company with a good reputation, Survey USA, as they describe a poll they conducted recently on the Los Angeles Mayoralty race:
Cell-phone and home-phone respondents included in this research: SurveyUSA interviewed 1,000 city of Los Angeles adults 04/08/13 through 04/10/13. Of the adults, 840 were registered to vote. Of the registered, 478 were determined by SurveyUSA to be likely to vote in the 05/21/13 runoff. This research was conducted using blended sample, mixed mode. Respondents reachable on a home telephone (82% of likely voters) were interviewed on their home telephone in the recorded voice of a professional announcer. Respondents not reachable on a home telephone (18% of likely voters) were shown a questionnaire on their smartphone, tablet or other electronic device.
One approach is clearly more sophisticated than the other. In the 2011 federal election the polls did not cover themselves with glory in terms of accuracy.  However, according to my calculations, Forum was eighth out of nine in total error on its national poll numbers.

Most of the other polls used online panels to conduct their surveys, a methodology that keeps getting better and allows better targeting. For example, the last Angus Reid survey was able to ask respondents only about parties actually running candidates in their constituency. Online polls, however, still can't guarantee their sample is fully representative of the population.