Intergenerational Analysis in the IDI




Barry Milne, Eileen Li, Irene Wu, Martin von Randow


University of Auckland: Andrew Sporle

University of Otago, Wellington: Sheree Gibb and Andrea Teng

University of Otago: Gabrielle Davie


This project aimed to investigate the extent to which intergenerational links are preserved using the collection of de-identified administrative data sets from the Integrated Data Infrastructure (IDI). Intergenerational links are important to assess such things as intergenerational transfer of wealth, socioeconomic mobility, and familial influences on health and wellbeing (both genetic and environmental).

Less investigated are multi-generational effects (spanning more than two generations). Our investigations of intergenerational effects in the IDI have a particular interest in multigenerational links to open up possibilities for research on:

  1. Assessing the multigenerational effect of socioeconomic status on health and other outcomes for those living today, e.g. does socioeconomic influence span two generations and more?;
  2. Documenting intergenerational residential mobility, e.g. via geographical similarity between births from succeeding generations; and
  3. Assessing whether the biological effect of parental age, e.g. on psychiatric disorders, extends across generations.

The data sets in the IDI have been linked at the person-level for the whole New Zealand population, and cover different timeframes. Specifically, the Department of Internal Affairs (DIA) data include birth information dating back to the 1840s, with unique IDs for the child and for both their parents where they exist. We have focused on the DIA data set as this is the only IDI data set with potential links prior to 1990, which covers most of the population (MSD records begin in 1990; Census records are only available for 2013).

Making use of these DIA intergenerational links, we sought to answer the following questions:

  1. How many generations can be determined?
  2. What is the total number at each generation?