Education data is great. But what you learn from it depends on what you want to see.

If you are an optimist, you will see the surge in students gaining a high school qualification since 2002 when the National Certificate of Educational Achievement (NCEA), New Zealand’s main school qualification, was introduced.

In 2004, 79% of students left school with at least an NCEA Level 1 certificate – the lowest of the three NCEA Levels 1 to 3 – typically achieved around age 15. By 2016, the figure had risen to 89%. Pessimists will see the falling student performance on international tests and worry about the slipping calibre of graduates. Realists will see the need for better measures to evaluate school performance to explain trends.

The Education Ministry and other agencies evaluating student outcomes have used attaining an NCEA qualification as the main indicator of school success. But because there are myriad ways of achieving an NCEA Level 1, 2, or 3 certificate, there can be substantial differences in performance among students with the same qualification (see Chapter 1).

Simply put, it is difficult to tell whether the surge in NCEA completion has been accompanied by more learning. Comparing and assessing performance between students in the same year, or across different years, is not a straightforward task when students take different combinations of hundreds of NCEA standards.

The New Zealand Initiative has developed a new measure of student NCEA achievement using Statistics New Zealand’s Integrated Data Infrastructure (IDI) data. We describe the measure in Chapter 2 and demonstrate its applicability in Chapter 3. No performance metric is perfect, but ours has a few advantages over other current measures.

This report also illustrates the potential opportunities in the rich data warehouse available for education policy research in New Zealand (see Chapter 4). This report does not assess New Zealand’s qualifications or assessment framework but rather better ways of using existing educational data.