An analysis of population lifetime data of South Australia 1841 - 1996

Abstract

The average length of life from birth until death in a human population is a single statistic that is often used to characterise the prevailing health status of the population. It is one of many statistics calculated from an analysis that, for each age, combines the number of deaths with the size of the population in which these deaths occur. This analysis is generally known as life table analysis. Life tables have only occasionally been produced specifically for South Australia, although the necessary data has been routinely collected since 1842. In this thesis, the mortality pattern of South Australia over the period of 150 years of European settlement is quantified by using life table analyses and estimates of average length of life. In Chapter 1, a mathematical derivation is given for the lifetime statistical distribution function that is the basis of life table analysis, and from which the average length of life or current expected life is calculated. This derivation uses mathematical notation that clearly shows the deficiency of current expected life as a measure of the life expectancy of an existing population. Four statistical estimation procedures are defined, and the computationally intensive method of bootstrapping is discussed as an estimation procedure for the standard error of each of the estimates of expected life. A generalisation of this method is given to examine the robustness of the estimate of current expected life. In Chapter 2, gender and age-specific mortality and population data are presented for twenty five three-year periods; each period encompassing one of the colonial (1841-1901) or post-Federation (1911-96) censuses that have been taken in South Australia. For both genders within a census period, four types of estimate of current expected life, each with a bootstrap standard error, are calculated and compared, and a robustness assessment is made. In Chapter 3, an alternate measure of life expectancy known as generation expected life is considered. Generation expected life is derived by extracting, from official records arranged in temporal order, the mortality pattern of a notional group of individuals who were born in the same calendar year. Several estimates of generation expected life are calculated using South Australian data, and each estimate is compared to the corresponding estimate of current expected life. Additional estimates of generation expected life calculated using data obtained from the Roll of Honour at the Australian War Memorial quantify the reduction in male generation expected life for 1881-1900 as a consequence of military service during World War I, 1914-18, and the Influenza Pandemic, 1919.