Opinion polling has been commissioned throughout the duration of the 48th New Zealand Parliament and in the leadup to the 2008 election by various organisations, the main four being TVNZ, TV3, The New Zealand Herald and Roy Morgan Research. The sample size, margin of error and confidence interval of each poll varies by organisation and date.
Refusals are generally excluded from the party vote percentages, while question wording and the treatment of "don't know" responses and those not intending to vote may vary between survey firms.