NCEA and University Entrance pass rates are lower than previously thought, with some dropping by as much 20 percentage points, a more accurate count has revealed.
The Qualifications Authority said national pass rates for the three levels of the NCEA and for UE were 0.2 to 0.9 percent lower under the new method for calculating the figures.
Pass rates for Asian students were down by 9.7 to 20.4 percentage points, and for Pasifika students by 3.3 to 7.8 percentage points.
Māori students' pass rates were 2.2 to 4.7 percentage points lower than previously calculated and the rates for Pākehā students were 1.7 to 3 percent lower.
The authority said the new pass rates were based on the total number of students in school each year, rather than on enrolments at 1 July.
It said the previous count missed about 10,500 students including 4000 Māori students.
The authority also separated the results of international and adult students from those of domestic school students, and changed the way students' ethnicity is allocated.
NZQA deputy chief executive Kristine Kilkelly for assessment said the new measure was more precise and counted all students on school rolls across the whole year.
"There are some changes in NCEA and UE attainment rates nationally, and most schools will see some changes as result of the new enrolment measure. But the overall amount of improvement in attainment over recent years is similar and continues to be positive," she said.
Ms Kilkelly said the biggest change was a 20.4 percentage point drop in Year 12 Asian students' attainment of NCEA level 2 last year, from 97.8 percent to 77.4 percent.
She said schools were told today what their achievement rates had been for each of the past 10 years under the new methodology and most would have seen only small changes in their figures.
"There will be a more significant change for some schools and that will generally be because they have smaller roll numbers and so any small changes will have a higher effect in terms of the statistics, but overall for many schools it's not a great deal of change," Ms Kilkelly said.
She said NZQA would use the new system to report achievement rates next year.
It would also stop reporting "participation-based" achievement rates, which were based only the number of students participating in each level of the NCEA and UE.
"Having more than one measure has been, I think, confusing so I believe it will be welcomed that we've moved to a simple, single measure," she said.