February 18th 2013: A lot of volatility in BC

If you follow this site (and politics in general) outside of electoral periods, you might have noticed that polls can be quite volatile. One good example is the Liberal Party of Canada that keeps varying from the low 20's to the low 30's depending on the poll/methodology/Justin trudeau mentionned/etc.

The situation is similar in BC. The election is about 3 months away. In politics, this is an eternity. And since our campaigns don't last 1 year, unlike in the United States, we don't have a lot of coverage and polls at the moment. However, the few we have are hard to interpret. Let's take a look.

We got our "regular" (in the sense that they have been releasing a poll every month or so for the last year) by Angus-Reid. We also got one from Justason (never heard of them before, I admit it), as well as one from Mustel. And finally, the most recent one from Ekos. Beside being not conducted at the same time, these polls vary by methodologies (online samples vs phone calls, sample size, questions asked, etc) and results. They all agree on having the BC NDP first with a comfortable lead over the Liberals, but that's pretty much it. Adrian Dix and his party vary from 48% in the Justason poll to 39% in the Ekos one. The lead can be as big as 22 points, or as small as 10 points.

Hopefully, this kind of volatility will be reduced the closer we get to election day. But I wouldn't necessarily count on it as the volatility probably comes primarily from the differences in methdologies. If it was purely coming from the natural statistical variation, we could solve this by averaging the polls. But recent electons in this country have shown that it can lead to large mistakes.

Use the simulator to see how much difference it makes to have a 10-points or a 22-points lead. You'll see that it can be huge in terms of seats. And let's not forget the "small" parties, especially the Conservatives. For them, being at 10 or 15% can make the difference between 0 and 5 seats, depending on how efficient (i.e: regionally concentrated) the vote could be.

As you may know, I do run simulations to calculate probbilities. Basically, I average the polls and I sample a 1000 times to reflect the natural statistical variation due to polls (i.e: the margin of error). I also account for the effect of the electoral system. As a general rule of thumb, the BC Liberals and Christy Clark have a chance as long as they are less than 10 points behind in the polls. More than this and the BC NDP has a 100% chance of winning. It becomes really interesting if the Liberals can come within 5-6 points of the NDP. There, the chances of winning are "real" (i.e: not like 0.1%, but as high as 5-10%).

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