A report suggesting radical reforms of the way teachers and schools are assessed has been shot down by those working in the sector.

The New Zealand Initiative, a market-oriented think tank, says existing measures of "success" are unfair on lower-decile schools, which are often achieving much better results than raw data would suggest.

It also wants a new way to assess the quality of teachers, by showing the impact they have on students' achievement, bearing in mind things affecting students outside school, or special learning needs.

The recommendations come in the think tank's third of three reports that have looked at the state of education, and what might be done to improve it.

The first report, in 2016, found 185 (or 8 per cent) of schools were failing, with one-third of those schools persistently failing students for at least a decade. The latest report, Amplifying Excellence, does not specify what that number is now.

Released on Thursday morning, it includes eight recommendations for the Government, to help promote "transparency, professionalism, and support in schools."

Report author Martine Udahemuka said schools looked as if they were failing if they did not meet certain targets, but that was without taking into account a community's circumstances.

Parents sometimes just looked at a school's decile number as a proxy for the teaching and learning happening there, but deciles were not an indicator of quality.

Some low-decile schools were achieving much higher than they might be expected to, and some high-decile ones were perhaps not pushing students as hard as they could.

Udahemuka said a fairer measure, which took into account all the other background factors that mattered to student achievement, should be created using data on students' backgrounds that was already held by Statistics New Zealand.

"[For example] this school should have 40 per cent leave with NCEA level 2 at the end of the year, and if the school had 60 per cent leave with level 2 it has over-performed, given the background of the students."

The report also suggests principals have full autonomy of a school budgets, despite school leaders last year banding together to protest against a proposal for a "global budget" for schools.

Post Primary Teachers' Association president Jack Boyle said the report seemed to work on the assumption there was a problem with the quality of teachers, which was not the case.

He did not agree a new measure would help parents judge the performance of a school. No amount of data could measure the difference a good teacher could make in a child's life, he said.

"Education is complex, rich, multi-layered."

The report suggests "exemplar" schools doing excellent work with students could support schools from similar communities that were underperforming, through the merger of their boards.

Boyle said the creation of Communities of Learning, whereby schools work together in clusters to share resources and expertise, had pre-empted that recommendation.

He believed the think tank had not talked to those working in education, but had instead "cherry-picked" overseas evidence to support its theory.

Education Minister Nikki Kaye said she was very interested in looking at what could be done to more accurately reflect the impact schools were having on their students, which meant being able to better measure the growth students were making.

"I also think it's vital that parents are provided with more information about how their child is progressing."

She said combining school boards would not be the answer for every school wanting to raise achievement, but might help those with a particular need.