Summarised by Centrist

In his article Polling 101: Chapter 3 – When can you trust the polls? Michael Wagener discusses some possible reasons the polls didn’t predict the outcome in NZ’s 2017 and 2020 general elections.

In New Zealand’s 2017 general election, the polls “significantly underestimated National” and “significantly overestimated Labour.”

In the 2020 election, most of the polling companies were off by 4 to 5% from the election results.

Large voter turnout and number of special votes

In NZ’s 2020 election there was large voter turnout, possibly because of the attached referendums (Cannabis and End of Life).

There was also a “huge number of special votes”, “over a quarter of the total votes cast”. Some of these were New Zealanders living abroad and others “new voters”. Special votes are hard to poll.

Special votes are usually in step with ordinary votes (when it comes to how parties are trending) but this was not the case in the 2020 election. The special votes heavily favoured Labour.

Read more over at The Blue Review