We often get asked about New Zealand school decile rating system. This system can be quite confusing and very misleading as to a schools performance.
It is important to understand that decile ratings are used by the New Zealand Ministry of Education for funding purposes only - they are not an indication of the performance or quality of education delivered at a school. It simply means that schools with a lower decile rating get more resource funding from the government to support their students' learning needs.
A school’s decile measures the extent to which the school’s students live in low socio-economic or poorer communities. Decile 1 schools are the 10% of schools with the highest proportion of students from low socio-economic communities. Decile 10 schools are the 10% of schools with the lowest proportion of students from these communities.
However, a decile doesn't indicate the overall socio-economic mix of the students at a school.
The best indication of a school's performance is through ERO Reports http://www.ero.govt.nz/ and http://www.nzqa.govt.nz/assets/About-us/Publications/stats-reports/ncea-annualreport-2015.pdf