文摘
Motivated by applications requiring quantile estimates for very small probabilities of exceedance pn≪1/n, this article addresses estimation of high quantiles for pn satisfying \(p_{n}\in [n^{-\tau _{2}},n^{-\tau _{1}}]\) for some τ1>1 and τ2>τ1. For this purpose, the tail regularity assumption logU∘ exp∈ERV (with U the left-continuous inverse of 1/(1−F), and ERV the extended regularly varying functions) is explored as an alternative to the classical regularity assumption U∈ERV (corresponding to the Generalised Pareto tail limit). Motivation for the alternative regularity assumption is provided, and it is shown to be equivalent to a limit relation for the logarithm of the survival function, the log-GW tail limit, which generalises the GW (Generalised Weibull) tail limit, a generalisation of the Weibull tail limit. The domain of attraction is described, and convergence results are presented for quantile approximation and for a simple quantile estimator based on the log-GW tail. Simulations are presented, and advantages and limitations of log-GW-based estimation of high quantiles are indicated.