The Education Minister has defended national standards despite an independent report finding teachers are ranking children's reading, writing and maths correctly only about 60 per cent of the time.
The report, commissioned by the Ministry of Education said teachers' use of the standards last year lacked dependability, Radio New Zealand reported.
The study was based on research involving 96 schools.
It said the proportion of poorly performing children who improved last year seemed unreasonably large.
Teachers' judgement lacked dependability and it was impossible to know how many of last year's national standards results were correct, the report said.
But Education Minister Hekia Parata told RNZ it was just the second year of reporting on the standards it needed time to improve.
The report was commissioned so the ministry could see where it needed to target its resources, she said.
"So it's been helpful in that regard."
The information was part of an "overall discussion" with teachers, Ms Parata said.
"National standards will get better and better as has happened with NCEA, as has happened with delivering the curriculum."
The standards had never replaced conversations parents could have with their children's teachers, and if parents had questions about their child's progress, that was still an option available to them, Ms Parata said.
"We're on a journey of continuous improvement."