Education sector union, NZEI, vice-president Frances Guy said the data should be read with caution.
"We're disappointed that they've been released in a form in which they will be used for league tables which will be very disruptive to education in New Zealand," she said.
"If there is an issue about not having good enough reporting on individuals then that needs to be dealt with, but standards isn't the way to do it."
A majority of local principals were at a conference in Australia and could not be reached for comment.
However, Hawke's Bay Primary Principals Association vice-president Mike Bain said there were fears the data would be used to unfairly compare schools.
The "untrustworthy" data could drive biased competition, he said.
Ms Guy said league tables used to rank schools told parents absolutely nothing about their child's progress.
"I can't see any good coming of them at all. It's all about setting up competition."
Mrs Parata said the results showed a "baseline of learner achievement" that would help those in need of extra of support.
However, opposition groups believe the data to be flawed as it not been trialled or moderated.