1 Introduction

This project aimed to investigate the extent of which intergenerational links are preserved using the collection of de-identified administrative datasets from the Integrated Data Infrastructure (IDI). Intergenerational links are important to assess such things as intergenerational transfer of wealth, intergenerational socio-economic 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 multi-generational links to open up possibilities for research on, e.g., (i) assessing the multi-generational effect of socio-economic status on health and other outcomes for those living today (e.g., does socio-economic influence span two generations and more?); (ii) documenting intergenerational residential mobility (e.g., by documenting geographical similarlty between births from succeeding generations); and (iii) to assess whether the biological effect of parental age (e.g., on psychiatric disorders)1 extends across generations.

The datasets in the IDI have been linked at the person-level for the whole New Zealand population and covers 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 focussed on the DIA dataset as this is the only IDI dataset 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: (i) How many generations can be determined? (ii) What is the total number at each generation?