Application of Age-Transformation Approaches to Mortality Projection for Japan

Futoshi Ishii, National Institute of Population and Social Security Research, Japan

In this paper, we will propose an application of age-transformation approaches for projecting mortality rates for Japan. The author already discussed that adding a feature of age-shifting structure to the Lee-Carter model could improve mortality projection for Japan. However, the proposed model used not only age-shifting but also age-scaling of mortality in fact, which would imply that these efforts to improve mortality model could be incorporated into a more general framework, i.e. age-transformation approach. From this viewpoint, we will describe these strategies to improve mortality model in the framework of age-transformation approaches, and reconsider the mortality projection model for Japan. Our results show that this approach works well for Japanese mortality data. If other developed countries experience the similar mortality improvement in the future as Japan did, the age-transformation approach explored in this article could be a strong and useful tool.