Analysis: How did you vote last time?

So I was thumbing through a recent poll, as I'm prone to do, when I noticed the "past federal vote" did not match up. In fact, it didn't match it's own math. It claims over 1400 respondents, yet, all responses only add to 1315.

So I did a bit of math. It turns out that only 36.58% claim to have voted Conservative last time, compared to the 39.62% that actually did. That in itself is not a "big deal"

However for the NDP it was worse, with only 23.95% saying they voted NDP, compared to the 30.63% that did in reality.

The Liberals, meanwhile, were over-estimated, with 22.5% claiming they voted Liberal, while only 18.9% did.

I thought maybe I'd have better luck comparing this to the 2008 results. That itself leads to problems, as the NDP took only 17.48% and the Liberals, 26.26%.

However I stuck on something odd...

The averaged 2011 and 2008 result.

According to that, 24% voted NDP. 24% claim to have voted NDP in the poll. 22.5% voted Liberal. 22.5% claim to have voted Liberal in the poll.


I'm not quite sure what this means, but I will continue to investigate. This averaging works for all parties except the Greens, which are consistently over-represented.