“Decile is not a proxy for school quality”. Principals, teachers and education professionals have said this for years, and yet students have been flocking out of low decile schools and into high decile schools all this while.

Decile drift is one of many issues highlighted in the 2018 Tomorrow’s Schools Taskforce Review.

Since 1995, when the decile funding model was implemented, the number of students in decile 8–10 schools has increased from 201,000 to 280,000; in contrast, the number of students in decile 1–3 schools has decreased from 188,000 to 179,000.

One consequence is socioeconomic segregation. Currently, decile 1–3 schools serve 24% of New Zealand students; at the same time, 45% of Maori students and 60% of Pacific students attend decile 1–3 schools.

Although education professionals have decried the use of decile as a proxy for years, no supporting evidence has been offered – until now.

Earlier this week, the New Zealand Initiative launched the first in a series of reports discussing the results from its ground-breaking school performance measurement tool. Tomorrow’s Schools: Data and evidence finally provides evidence debunking the myth that decile is a proxy for school quality.

The results from our data-driven research show that once you separate the effects of factors over which secondary schools have no control, like family background, there is no difference in average school effectiveness across deciles.

In other words, low decile schools perform just as well as high decile schools, given the different communities each school serves.

Sadly, while the Review criticises decile drift, the Taskforce’s recommendations neglect its origin – the failure to provide better information about a school’s true performance.

Instead of blaming parents, or seeking to artificially restrict choice, the Taskforce should be calling for better information – exactly what the Initiative is doing. We have already shown the Ministry of Education what they can do with the data that already exists.

Crucially, while our results show that average school performance is comparable across deciles, the Initiative believes our education system still needs improvement. Children from disadvantaged backgrounds still underperform in both domestic and international education figures.

Our tool is one method to improve outcomes for these students. The Ministry should use our tool to identify the top-performing low-decile schools and find out what works so we can achieve a more equitable education system in New Zealand.

The Initiative had already put in the hard yards; it is for the Ministry to act now.

To read Tomorrow’s Schools: Data and evidence, click here.