Using the age-and sex-specific data of 14 developed countries, we compare the point and interval forecast accuracy and bias of ten principal component methods for forecasting mortality rates and life expectancy. The ten methods are variants and extensions of the Lee-Carter method. Based on one-step forecast errors, the weighted HyndmanUllah method provides the most accurate point forecasts of mortality rates and the LeeMiller method is the least biased. For the accuracy and bias of life expectancy, the weighted Hyndman-Ullah method performs the best for female mortality and the LeeMiller method for male mortality. While all methods underestimate variability in mortality rates, the more complex Hyndman-Ullah methods are more accurate than the simpler methods. The weighted Hyndman-Ullah method provides the most accurate interval forecasts for mortality rates, while the robust Hyndman-Ullah method provides the best interval forecast accuracy for life expectancy.
IntroductionIn recent years, the rapid ageing of the population has been a growing concern for governments and societies. In many developed countries, the concerns are concentrated on the sustainability of pensions and health and aged care systems, especially given increased longevity. This has resulted in a surge of interest among government policy makers and planners in accurately modeling and forecasting age-specific mortality rates. Any improvements in the forecast accuracy of mortality rates would be beneficial for policy decisions regarding the allocation of current and future resources. In particular, future mortality rates are of great interest to the insurance and pension industries. Several authors have proposed new approaches for forecasting mortality rates and life expectancy using statistical modeling (see Booth 2006; Booth and Tickle 2008, for reviews). Of these, a significant milestone in demographic forecasting was the work of Lee and Carter (1992). They used a principal component method to extract a single timevarying index of the level of mortality rates, from which the forecasts are obtained using a random walk with drift. Since then, this method has been widely used for forecasting mortality rates in various countries, including Australia The strengths of the Lee-Carter (LC) method are its simplicity and robustness in situations where age-specific log mortality rates have linear trends . A weakness of the LC method is that it attempts to capture the patterns of mortality rates using only one principal component and its scores. To address this, Hyndman and Ullah (2007) propose a model that utilizes second and higher order principal components to capture additional dimensions of change in mortality rates. Although other methods have been developed (e.g., Renshaw and Haberman 2003a,b,c;Currie, Durban, and Eilers 2004;Bongaarts 2005;Girosi and King 2008;Renshaw and Haberman 2006;Haberman and Renshaw 2008;Ediev 2008), the LC method is often considered as the benchmark method. For example, the LC method is compared with other approach...