Using Cohort Change Ratios to Estimate Life Expectancy in Populations with Negligible Migration: A New Approach

David A. Swanson, University of California, Riverside
Lucky M. Tedrow, Western Washington University

Census survival methods are the oldest and most widely applicable methods of estimating adult mortality and for populations with negligible migration they can provide excellent results. In this short note, we demonstrate that life expectancy at birth can be computed by using census survival rates in combination with an identity whereby the radix of a life table is equal to 1. We show how this is derived. We compare estimates using our approach against other estimates and find it works reasonably well. As well as some nuances and cautions, we discuss benefits in using this approach to estimating life expectancy, including the ability to develop estimates of average remaining life at any age. We believe that the technique is worthy of consideration for use in estimating life expectancy in populations that experience negligible migration.