著書

This book describes a novel method for mortality modeling applying the shifting feature of the mortality curve. In Japan, the increase and pace of the extension in life expectancy have been quite remarkable. Therefore, existing mortality models often cannot capture the peculiarities of Japanese mortality, nor can the Lee–Carter model, which is now regarded internationally as a standard model. One of the important concepts to model recent Japanese mortality is a shifting feature. In this book, the linear difference model, which has many advantages for modeling and analyzing Japanese mortality, is introduced. The book shows applications of the model to mortality projection with a tangent vector field approach and decomposition of the change of modal age at death. The models introduced here are useful tools for modeling mortality with strong shifting features, as in Japan.

In this chapter, we use censuses, lists of centenarians, and vital statistics to describe the demography of centenarians, defined as the group of people who are 100 years old or older. We also refer to the group of people between the ages of 105 and 109 as semi-supercentenarians. Finally, we refer to those individuals who reach the age of 110 and beyond as supercentenarians. Although our ability to describe centenarians using these data is currently very limited, censuses and the lists of centenarians can be used to determine the number of people who survive to age 100 or older. Moreover, vital statistics provides the number of deaths, by single year of age and by sex, for those who died above the age of 100 since 1899. Our study examines trends in the highest ages at death for each year between 1963 and 2015, and shows increasing trends during this period. Using the number of deaths and applying the extinct cohort method, we estimate the level of mortality of people aged 100 or older, as well as trends in mortality. We observe decreasing trends in mortality levels among people who have reached very high ages, even as mortality continues to increase with age until very high ages.