Monday, April 29, 2013

B.C. race tightens, but NDP still in control

Though the margin between the B.C. Liberals and B.C. New Democrats has tightened since the last projection update of Apr. 19 (based on polling data running up to Apr. 14), the NDP remains the odds-on favourite to win the election of May 14.

The New Democrats are now projected to take 47.6% of the vote, down 0.3 points from Apr. 19. The Liberals gained 2.8 points to hit 32.4%, the highest they have been since mid-January, while the B.C. Conservatives dropped 3.3 points to 8.5%. The B.C. Greens fell 0.7 points to 8.2% in the projection, while support for independents and other parties increased to 3.4%.

The NDP is now projected to win 59 seats, down six, while the Liberals are pegged to take 25. The ranges have widened considerably, to between 45 and 75 seats for the New Democrats and between eight and 39 seats for the Liberals. The Greens are now projected to be capable of winning as many as three seats with current polling support.

There are some important reasons why the projection and forecast ranges have increased so dramatically, and support for the Conservatives and other parties has changed so much.

First, the methodological shift in the projection. As the official list of candidates was released over the weekend, the projection model has been updated to accurately reflect the field of candidates that British Columbians will be able to vote for on May 14. In the case of the independents and fringe parties, this allowed me to estimate how much support they will get in each riding and, therefore, in each region of the province. This is why support for independents and other parties has increased from 1.8% to 3.4%. 

More importantly, an adjustment has been added to the vote projection model to take into account the fact that the Conservatives have put up only 56 candidates. That means they are running in only 66% of ridings, making it extremely unlikely that they will be able to take as much of the vote as the polls are awarding them. Most respondents who intend to vote Conservative likely have no idea whether or not there will be a Conservative name on the ballot, and if they find out between now and the election their change in support will not be reflected. And, in the past, there has been a strong correlation between polls over-estimating a party's support and a less-than full slate. Accordingly, the Conservatives will now have the "no seat in the legislature" adjustment applied to their polling numbers, which means a reduction by a factor of 0.73.

Lastly, because of the updated candidates list, the projection has to be tweaked to ensure accurate distribution of support. For example, prior to this update Green support was spread over the 14 ridings in the Vancouver Island region. But since they are only running 11 candidates in the region, that same support needs to be distributed over 11 ridings instead. All else being equal, that increases their support in each riding where they have a candidate. The same has had to be done to the Conservatives.

As for the wider ranges, this is due to the campaign having started and the numbers of polls having dropped. Prior to an election campaign, the projection model reduces the weight of a poll with each passing week. During a campaign, that weight is reduced by the same amount each day. The projection has had only two polls added that were taken during the campaign (Angus-Reid, Apr. 24-25 and Justason Market Intelligence, Apr. 15-23) meaning that the pre-campaign polls now have an extremely low weight in the model. And as the projection dates a poll by its median date, that means the Justason poll is considered six full days older than the Angus-Reid poll. That reduces its weight considerably, and results in the Angus-Reid poll taking up roughly 93% of the aggregation right now. Due to the Angus-Reid being almost the only poll being considered by the model, the uncertainty of where the parties currently stand is very high.

This will undoubtedly change as more polls are released to capture the effect of tonight's debate. But keep that in mind when looking at the numbers in this latest update.

The Justason poll, released today via The Tyee (surveying 600 via telephone and internet), is interesting as it shows the NDP with a 22-point lead. That is unchanged from Justason's last poll from the end of January, suggesting that little has changed since then. Justason gives the NDP 49% to 27% for the Liberals, 12% for the Greens, and 11% for the Conservatives. Like other surveys, it shows the Greens doing very well on Vancouver Island.

The Angus-Reid poll was released on Friday via CTV and The Globe and Mail (surveying 812 via their online panel) but was conducted more recently than Justason's survey. The poll gives the NDP 45%, the Liberals 31%, the Conservatives 11%, and the Greens 10% support.

Compared to Angus-Reid's last survey taken just before the campaign began, that represents a gain of three points for the Liberals, a drop of one point for the Conservatives, and a decline of three for the Greens. The NDP held steady.

A sign that the Liberals are making up ground on the New Democrats? We will have to see what other surveys show, as the three-point increase in Liberal support is within the margin of error (or would be, if the sample was probabilistic). There is good reason to suspect a statistical wobble, as the Liberals have been hovering between 28% and 31% in Angus-Reid's polls going back to November 2012, and the Justason survey suggests no reason to believe there has been a big change in voting support. 

Also of note are two riding polls that were released by the Prince George Citizen last week for the ridings of Prince George-Valemount and Prince George-Mackenzie. Conducted by Oraclepoll on Apr. 17-20 and Apr. 15-18 (respectively) and surveying 300 people in each riding, the survey found the Liberals narrowly ahead. In Prince George-Valemount, incumbent Liberal Shirley Bond had 46% to 41% for the NDP's Sherry Ogasawara and 10% for the Conservative candidate. In Prince George-Mackenzie, rookie Liberal Mike Morris had 44% to 37% for the NDP's Bobby Deepak, 14% for the Conservative candidate, and 5% for the Greens.

In part due to these two polls, but also the better Liberal numbers in the Interior/North in both the Justason and Angus-Reid polls, the two Prince George ridings have gone over to the Liberals from the NDP in the projection. But the results of these surveys are similar to the ones that were done for the two Kamloops ridings, showing stronger Liberal support than expected. Perhaps this is a methodological bias on Oraclepoll's part, or perhaps this is a sign that the Liberals will not be easy to defeat in the Interior and North. It is something to keep an eye on.