Rob Salmond at Pundit looks at the polls, and linear projection of where the parties may end up on election night, being:
He comments further:
Using the analysis above, we project that New Zealand First will get 3.8% of the vote. We can also project with 95% confidence that the party will get between 2.3% and 5.2% of the vote. Importantly, we project that there is only a 4% probability New Zealand First will get more than five percent of the vote.
Of course this is all based on the trend of the last few weeks continuing in the last week, and it may not continue if events get in the way.