Summary

The ability to link students helps us to answer important questions about the performance of New Zealand's tertiary education system, such as what proportion of students complete their qualification, how long do people study for, or how much funding does not result in some form of recognised achievement.

Up to 2003, the lack of a unique national student number limited our ability to answer such questions in a systematic or complete way. In 2003, two things happened to change this. National student numbers (NSNs) were introduced, and a statistical matching process was developed to estimate unique student numbers (which were called 'SNs'), that would link students enrolled without NSN before 2003.

This derived linking variable has been used for a range of subsequent research and analysis. National estimates of the rates of retention and completion were published in 2004, along with the rates that students progress to further study after completion. A number of additional longitudinal pathway studies have been undertaken using SN. These analyses have provided further new perspectives on the performance of the tertiary education system in New Zealand. In 2007, the Tertiary Education Commission began using this data to inform discussions with Tertiary Education Organisations around the monitoring of selected key performance indicators.

The original matching algorithms were developed in 2003 before the availability of NSN. The availability of four years of NSN data was able to provide a powerful independent means to measure the accuracy of the matching, and to revise the match weights and processes used. The methodology was extensively reviewed in 2007 and SNs were regenerated for all existing historical enrolments and completions data.

This was the first major review of this matching since it was first developed in 2003. The review has led to a measurable improvement in the quality of the linking, and to improved statistics on qualification completion and attrition which are also available on this website. This report documents this review, the quality of the revised matching, and its subsequent impact on student counts and rates of completion and attrition.