Cumulative income is calculated through the summation of previous years' average income. Due to limitations in Ministry of Education secondary school records which are only reliable after 2006, we move our window to 19 year olds from 2009, 2010 and 2011. This allows us to see the NCEA Level 2 results of our cohorts, and a more recent picture of training outcomes. The more recent window, however, limits us only to see forward to the age of 26.

We conduct the same exersise as before with this new window, classifying 19 year olds with a heirarchy of:

1. Industry Training Organisation
2. University
3. Institute of Technology or Polytechnic
4. College of Education
5. Private Training Organisation
6. Wananga
7. Within IRD tax records (No training enrolments)

Within these groups we look back to see if they completed NCEA Level 2, and if so, at what level was it awarded. Note that NCEA Level 2 not-achievers cannot be distinguished from individuals who sat alternative secondary school programmes such as Cambridge or home schooling programmes, and thus are ignored in this analysis. Due to the low number of excellence students, these were combined with merit achievers.

Within these groups we check if they have completed a qualification with the providers. Each subsequent year we track total yearly income of each individual still actively enrolled in study or earning income in IRD tax records, thereby removing anyone from the analysis that moves overseas or otherwise is lost from records. Across the groups we summarise the average earnings at each age.

Only income from Student Allowance, Wages and Salaries, and Business Income of the source codes ('C00', 'C01', 'C02', 'P00', 'P01', 'P02', 'S00', 'S01', 'S02') are considered. An individual is only classified as actively in IRD records from earning one of these sources each year.