Examining Mortality Transition in Brass Logit Space

Yong Cai , University of North Carolina at Chapel Hill
Hui Zheng, The Ohio State University

We examine mortality transition using Brass Logit Model. Building on Brass’s (1968, 1971) observation that the age pattern of mortality in logit scale can be summarized by a simple linear relation with two parameters, one for level, and the other for shape, we define the Brass Logit Space as delineated by possible combinations of the two parameters. We apply the Brass Logit Model to the empirical life tables assembled by the Human Mortality Database to examine how mortality transition plays out in the Brass Logit Space. We find that mortality transition takes place in a restricted band within Brass Logit Space and proceeds with strong regularities. Our analysis shows that while mortality transition tends to be driven primarily by level changes, it is important to capture shape changes for accurate depiction for mortality pattern. We propose a modified Brass Logit Model for the purpose of diagnosis and projection.

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 Presented in Session 15. Mortality Models