Hawke's Bay principals say pre-released National Standards prove data is flawed and not a reliable measure of student achievement.
Full results of the achievement of Years 1 to 8 students in reading, writing and mathematics will be released by the Ministry of Education on Friday, when they are made public on a government website.
However, during the weekend media outlets published results obtained from Official Information Act requests.
Prime Minister John Key said yesterday he welcomed debate generated by the publication of national standards data that measured, monitored and reported where help was needed.
Puketapu Primary School principal Chris Fox said there was much more to achievement that data could not show.
"We are very rigorous in the way in which we tally the standards but our interpretation of the standards may be different in the fact that one school's 'below' may be another school's 'at'," he said.
Students at the decile nine school achieved 87 per cent in reading, 75 per cent in writing and 78 per cent in mathematics.
"The standards themselves are a little bit flawed and the data is open to interpretation.
"The data is subjective, the reliability and validity of it - well there is little reliability or validity - so parents should see other measures of schools by going to the school and talking to the principal and teachers and children at that school."
"We also address standards in ICT and science and so we are pushing our expectations of high standards further out beyond those three areas of National Standards."