Introduction

According to the 2018 Programme for International Student Assessment (PISA), most of the variation in reading achievement in New Zealand was attributed to differences in performance between students within the same schools rather than differences between schools. This means that the average New Zealand school educates students with a wider range of ability than most other countries. Consequently, schools may be sorting students within their schools to manage diversity of needs, a practice which itself could lead to other social and academic effects.

Key findings

• Some school selectivity exists in New Zealand: two-thirds of students’ principals considered a student’s residence and half considered a student’s academics when admitting them.
• Since 2009, consideration of students’ academics when admitting students has increased.
• Given the amount of selectivity in New Zealand, one would expect more homogeneity in ability within schools. Other factors are at play to explain the large within-school variation in performance.
• Internationally, lower rates of academic consideration was associated with greater equity, while greater
  residential consideration was associated with greater reading performance.
• While not related to within-school variation in performance, New Zealand had higher than OECD average levels of public schooling, competition for students, and ability grouping of students.
• Grouping students by ability for all subjects was associated with lower reading performance across all countries and economies, while ability grouping within classes for some subjects was associated with higher reading performance. In New Zealand there was no association with performance.