School principals hope the news media will find it too difficult to turn their national standards results into league tables.
Schools must send their annual reports, including figures on students' performance in reading, writing and maths, to the Ministry of Education by the end of the month.
Opponents of the standards worry that league tables will be used to make invalid comparisons between schools.
But the Principals Federation says the tables might be hard to construct because schools are reporting their figures in different ways and with a lot of detail.
The Ministry of Education says it will use the results to measure national performance against the standards.