Almost 200 schools have not been included in official National Standards information after failing to provide the right details.
Data for 1899 primary and intermediate schools was made available on the National Standards website, Education Counts, yesterday.
But 188 schools have not been included because of a lack of information provided.
It is understood many schools are liaising with the ministry. However, others will not be included this year because of circumstances that meant they could not collate any data last year.
Several schools who spoke to the Weekend Herald said they did not send any data in because of unforseen circumstances including a computer glitch, staffing issues and changes in principals. One school did not send any data in because of the untimely death of its headmaster.
Principals yesterday maintained their stance that the data did not show anything new.
Manurewa East School principal Phil Palfrey said the data merely showed the difference between the haves and the have-nots.
"I've always ... believed in equity. We're in a low decile area and the reality is, we're always trying to get the children to achieve.
"Sometimes the big goal for teachers is to make sure the kids have a great day and are happy."
Manurewa East School sits in a low decile area in Auckland. The majority of its students are Maori or Pacific Island and for most pupils, school is their sanctuary, Mr Palfrey said.
The school's results showed the majority of its students were below the national levels in writing and reading and only slightly better in mathematics.
Mr Palfrey said many of his students arrived at school well below where they should be.
"The question then becomes, is it the fault of the early childhood centres? Are these children even getting that early childhood education?"
Over the bridge at decile 10 school Campbells Bay, on the North Shore, the results are stellar.
Most of the students are achieving above national standard levels in literacy and maths. But that doesn't mean it is all black and white, said principal John McGowan.
"We already know our students are well above where they should be, because we focus on monitoring our students ... we're not interested in comparing them to the kids down the road or over the bridge."
The data released yesterday show exactly what schools have sent to the ministry. Some schools have broken the figures down in percentages and the number of students achieving either well below, below, at, above, or well above the national standard.
Other schools have entered their own targets, such as "working towards" or "needing improvement" instead.
A search tab allows a reader to look up a particular school and see exactly how its students are achieving based on the National Standards.
When the tab is clicked on, however, a message pops up, warning: "Interpreting the data: Care needs to be taken when considering national standards data."
On the web: www.educationcounts.govt.nz