Abstract:

A random vector $X$ is a normal meanvariance mixture provided $X$, for a given $W \geq 0$, follows a multivariate normal distribution with mean vector $\mu + \beta W$ and covariance matrix $W\Sigma$, and provided $W$ follows a distribution $F$ on $[0,\infty)$. This provides a very flexible family class and by properly choosing the parameters and mixing distribution, many wellknown multivariate distributions can be obtained. A prominent example is the generalized hyperbolic (GH) distribution, when the mixing distribution is generalized inverse Gaussian. In this work, we study the tail dependence properties of the GH distribution and derive its coefficient of tail dependence, which controls the joint tail decay rate. We also investigate the tail dependence structure of normal meanvariance mixtures without assuming specific mixing distributions. That is, the relation between the tail behavior of the normal meanvariance mixture and its mixing distribution is deduced. Based on this result, a spatiotemporal model for extremes is proposed.
