Tried posting this elsewhere but the post wasn’t there when I looked from my work computer, so thought I would post here to see if it appears.

This is a really interesting chart. A question though: What about when polling companies review and tweak their approaches in the period following the election? I imagine that most worthy pollsters do this, because after three years they finally have some benchmark data and they can test different theories about what produces the error for certain parties, and make little adjustments to try and correct for it. Case in point – I was slightly suprised to see how close the most recent TV1 and TV3 polls were (although they were a week or so apart so that may explain it).

There are only really four points (on the chart) that can be used to estimate the error for each poll, but aspects of their polling approach may change (possibly a few times) between each election. The error for some of the parties in some of the poll curves looks larger than the difference between those polls and the last Election Day result, so does this chart simply assume that all methodolgies stay the same all of the time?

Perhaps some assumptions about this at the bottom of the chart would be good (just prevents it from being a tad misleading, and detracting from how interesting that chart really is). Just my two cents.

Cheers

The whole point of doing this sort on analysis is not to read too much into a few polls. However, with that in mind, ONCB and 3NRR have both seen a four percentage point drop in National support over their last two polls.

So I think “drastic downturn” is probably a fair summary of National’s recent poll results.

Behavioural responses and dynamics of effect re scandal and issue would also would be interesting; did I vaguely recall our host illuminating on this previously..