The Integrated Data Infrastructure (IDI) is a collection of de-identified administrative datasets, linked at the individual level for the whole New Zealand (NZ) population. In the current study, we used the IDI to investigate inequality in public service use within a 10 year period (July 2006 – June 2016) in the NZ population. Using a birth cohort approach, all individuals born in NZ between 1950 and 1984 were included in our sample. To investigate inequality in public service use, we calculated the concentration in service use within five public sectors (social welfare, hospitalisations, pharmaceuticals, accident compensation corporation (ACC), and criminal convictions). This was done for the whole sample, and broken down by age bands and sex. We also determined the concentration in cost accounted for by high service users within each sector.
Here, I will cover how we calculated service use within the five public sectors, how we identified inequality/concentration in service use, and describe the methods used to monetise service use for individuals in our cohort. I will also discuss the strengths and challenges associated with using large administrative data in a study of this nature.