We consider the problem of optimal stopping of a finite sequence of dependent random variables. We explicitly determine the maximum of the stopping value within the Fréchet class of all multivariate distributions with given continuous marginals. We show that the maximum is attained for a...

In this paper the meaning of the stochastic ordering relation is studied when the random vectors which are compared are assumed to be permutation symmetric. It is shown that in order to establish the stochastic ordering relation between two such random vectors it is enough to consider only upper...

We provide a simple characterization of the zonoid, lift zonoid, Lorenz zonoid of a random vector, as defined by Koshevoy and Mosler (J. Amer. Statist. Assoc. 91 (1996) 873; Bernoulli 4 (1998) 377). This characterization allows a direct use of Lyapunov's theorem on the range of nonatomic vector...

Several well-known stochastic orderings are defined in terms of iterated integrals of distribution or survival functions. In this note we will provide necessary conditions for some variability orderings of the above type. These conditions will be based on the comparison of mean differences,...

Von Plato (1991) has recently proposed a necessary condition for the infinite extendibility of a partially exchangeable {0, 1}-valued random vector. This paper will prove necessary conditions for the finite extendibility (of any order) of a partially exchangeable process of real-valued (not...

We consider a finite sequence of exchangeable binary random variables and assume that the conditional expected value of each variable is an average of the observed frequency of success and a prior guess. We obtain a representation of the law of the finite sequence as a beta-binomial. In this way...

A lower bound for the distribution function of a k-dimensional, n-extensible exchangeable process is provided when the marginals are uniform on the unit segment. The result is obtained by means of standard linear programming techniques. The lower bound for infinitely extendible exchangeable...