Friday, July 9, 2010

Projection Update

Due to the effect mentioned in the update to the previous post, the numbers that I backed out for the first week of the most recent EKOS poll are not reliable. Thus, it is not appropriate to treat the two weeks as separate polls. However, given that we do have separate information about the most recent week, which I would like to weigh a bit more, I will also not treat the two weeks as one poll. Rather, this is what I'm doing: I am giving a weight to the two-week numbers, and an additional weight to the most recent one-week numbers. The 34-day depreciation period is calculated from the midpoint of the most recent week: although the sample size is small by EKOS standards, it is actually slightly larger than most full polls by Nanos, Ipsos and Angus.

(Specifically, the sum of the two weights is the same as the weight of the two-week poll if one-week numbers hadn't been released. 62% of that sum is the two-week number, while 38% of it is the most recent week's.)

This modification does not change the seat projection:

CON - 136
LIB - 77
BQ - 55
NDP - 40

However, the average national Tory lead is 7.3% (instead of 7.4%).

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