Motivated by a recent discovery that the two-step inference for the Lee–Carter mortality model may be inconsistent when the mortality index does not follow from a nearly integrated AR(1) process, we propose a test for a unit root in a Lee–Carter model with an AR(p) process for the mortality index. Although testing for a unit root has been studied extensively in econometrics, the method and asymptotic results developed in this paper are unconventional. Unlike a blind application of existing R packages for implementing the two-step inference procedure in Lee and Carter (1992) to the U.S. mortality rate data, the proposed test rejects the null hypothesis that the mortality index follows from a unit root AR(1) process, which calls for serious attention on using the future mortality projections based on the Lee–Carter model in policy making, pricing annuities and hedging longevity risk. A simulation study is conducted to examine the finite sample behavior of the proposed test too.

Let (X1, …, Xn) be a multivariate normal random vector with any mean vector, variances equal to 1 and covariances equal and positive. Turner and Whitehead [9] established that the largest order statistic max{X1, …, Xn} is less than the standard normal random variable in the dispersive order. In this paper, we give a new and straightforward proof for this result. Several possible extensions of this result are also discussed.

This research was conducted to assess the location of population groups and conservation issues affecting dugongs Dugong dugon along the eastern Gulf of Thailand off Cambodia and Phu Quoc Island, Vietnam. Interviews in fishing communities in 2002 and 2004 along the Cambodian coast revealed that dugongs are sporadically found in fishing nets and their body parts are sold for a relatively large profit. During 4 days of aerial surveys in Cambodia in 2004 we saw no dugongs. We interviewed villagers in Phu Quoc Island, Vietnam, in 2002 and learnt that dugongs are regularly found and hunted, again for high profits. In both countries we recommend that legislation addressing threatened species be strengthened and enforced. In collaboration with the Cambodian and Vietnamese governments and NGOs, we propose the exploration of alternative non-destructive fishing methods and the initiation of an education campaign based on conservation of marine wildlife and the nearshore environment. National and transboundary management and community-based conservation are required in conjunction with strategies to address overfishing and poverty.