Measures of Lifespan Length and Variation Using a Mixture Model: The Case of Egypt
-
Marwah S. Siam
,
Hussein A. Sayed
Abstract
Monitoring the changes in mortality patterns and levels requires studying mortality models and measures of lifespan length and variation. Measures of lifespan length and variation can be obtained from life tables or from mortality modes. In this paper, measures of lifespan length and variation are presented for mixture model introduced by Zanotto, L., V. Canudas-Romo, and S. Mazzuco. 2021. “A Mixture-Function Mortality Model: Illustration of the Evolution of Premature Mortality.” European Journal of Population 37 (1): 1–27. This was applied to the case of Egypt for males and females in the period 1950–2021. The mixture model was able to fit Egypt’s mortality pattern well for both males and females. The calculated measures of lifespan length and variation show that there is an increasing longevity and a declining variation of age at death distribution across time for both males and females.
Acknowledgments
The authors would like to thank the Editor and the anonymous reviewers for their helpful and insightful comments.
Appendix A
Siler (1983) introduced a hazard model that fits the whole lifespan. It was fitted and compared with our mixture model as shown in Figure A-1. Siler model was not stable across years for both males and females and did not fit the data well. It overestimated the deaths at infant and child for males in 1950. There is high overestimation also in the infant and child mortality for both males and females in 2021. This happened along with underestimation of the modal age at death distribution and estimated lower deaths in the early years of adult age for both males and females, however, it was more visible in females. Also in the fitting procedures, Siler model was sensitive to any changes in the optimization method and the lower and upper bounds defined for each parameter for the optimization process. This happened because of the high correlation across Siler’s model parameters.
Comparison between fitted mixture model, siler model, and death function in life table for selected years.
Nevertheless, Siler model was used to estimate measures of lifespan length: life expectancy at birth and modal age at death distribution. It is clear in Figure A-2 that the Siler model is not stable and random, except for the increasing trend in the life expectancy. These fluctuations are a result of the poor fitting because of the correlation across the parameters and the inability of the model to capture the pattern of mortality. Measures of lifespan variation used in this paper depend on the measures of lifespan length which resulted in random pattern. Hence, it is expected that the measures if lifespan variation will result in a random pattern also.
Evolution of life expectancy at birth (e0) and modal age at death (M) from mixture model, siler model, and deaths from life table.
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Articles in the same Issue
- Frontmatter
- Editorial
- Editors’ Note
- Articles
- Is Intending to Have Children Rightist? A Research Note on Political Ideology and Fertility Intentions
- From Gerontocratic Rule to Political Adultism: The Experiential Bias in Germany’s Aging Electoral Democracy and the Limitations of a Vote 16 Policy
- Demography, Economy and Policy Choices: The Three Corners of the Pension Conundrum
- Regular Articles
- Measures of Lifespan Length and Variation Using a Mixture Model: The Case of Egypt
- Asymmetric Impact of Financial Development on Economic Growth in Mauritius
