Analysing and understanding changes in "fixed" characteristics over time: The value of longitudinal data
Creators: name: Campbell, Paul
Publisher: name: The Australian National University
Year: 2022

description: Over the life-course, people change. Changes span circumstances, demographic characteristics, and individual preferences, attitudes and behaviour. The work in this thesis centres on understanding such change, and in particular, changes in constructs that are often taken to be fixed. It harnesses cross-sectional and longitudinal datasets to demonstrate change. It seeks to link change at the individual-level with broader demographic processes. The studies focus on four constructs: migration (intentions, certainty, and outcomes), attitudes to immigration, Indigenous identification, and personality. Each are studied using longitudinal data. In the case of Australian Indigenous identification, the work presented is the first that has directly observed change, using a large, nationally representative longitudinal dataset. Identification change has long been cited as a likely source of Indigenous population growth, but had not previously been observed directly. In the case of personality, the Big Five personality traits are lauded for both their predictive validity and their stability across the life-course, though recent research suggests they do change over time. This thesis looks to contribute to a growing body of research assessing the stability and pattern of change of personality traits over the lifespan, assessing change attributable to age, to life events and change in circumstance. The studies also consider the relationship between individual-level psychological constructs and broader demographic outcomes, including migration intention, behaviour, and attitudes to immigration. This research shows that dispositional traits demonstrably predict differences in migration intentions, certainty, and outcomes. They also affect the strength of relationship between migration intention and subsequent migration. Changes at the individual level can have important implications at the population level, and longitudinal change has implications for cross-sectional analysis. In quantitatively assessing change in Indigenous identification, this work demonstrates that new identification appears to account for a considerable proportion of the growth in the Indigenous population. The newly identified group also appear to possess different characteristics to those who consistently identified as Indigenous across the two time points. In the case of Indigenous Australians, identification change can affect change in health and socioeconomic outcomes at the population level, observed in multiple cross-sectional analyses. That is, improvements over time in life outcomes may in part be attributed to changes in the demographic identifying as Indigenous. Changes in personality traits, particularly change driven by life events typically predicted by scores on the Big 5, introduces endogeneity between personality and life events, and this should be considered when personality is used to predict life outcomes. The studies utilise several large datasets, each with a unique profile of scope and collection methodology. Attention is given to the relationship between datasets and analysis, and how analysis can be used to validate data, particularly probabilistically linked longitudinal data. Changes in seemingly fixed attributes can be analysed meaningfully, particularly as more longitudinal datasets become available. The implications of such analysis stretch far, and longitudinal change should be considered in cross-sectional research.