A century ago, when Student’s t-statistic was introduced, no one ever imagined its increasing applicability in the modern era. It finds applications in highly multiple hypothesis testing, feature selection and ranking, high dimensional signal detection, etc. Student’s t-statistic is constructed based on the empirical distribution function (EDF). An alternative choice to the EDF is the kernel density estimate (KDE), which is a smoothed version of the EDF. The novelty of the work consists of an alternative to Student’s t-test that uses the KDE technique and exploration of the usefulness of KDE based t-test in the context of its application to large-scale simultaneous hypothesis testing. An optimal bandwidth parameter for the KDE approach is derived by minimizing the asymptotic error between the true p-value and its asymptotic estimate based on normal approximation. If the KDE-based approach is used for large-scale simultaneous testing, then it is interesting to consider, when does the method fail to manage the error rate? We show that the suggested KDE-based method can control false discovery rate (FDR) if total number tests diverge at a smaller order of magnitude than N3/2, where N is the total sample size. We compare our method to several possible alternatives with respect to FDR. We show in simulations that our method produces a lower proportion of false discoveries than its competitors. That is, our method better controls the false discovery rate than its competitors. Through these empirical studies, it is shown that the proposed method can be successfully applied in practice. The usefulness of the proposed methods is further illustrated through a gene expression data example.

We obtain simple non-parametric estimators of Gini-based covariance, correlation and regression coefficients. We then establish the consistency and asymptotic normality of the proposed estimators. We provide an explicit formula for finding the asymptotic variance of the estimators. We also discuss jackknifed versions of the proposed estimators for reducing the bias of the estimators in case of small sample sizes. Finally, we evaluate the finite-sample performance of these estimators through on Monte Carlo simulations from a bivariate Pareto distribution.

Gibbs-type random probability measures, or Gibbs-type priors, are arguably the most “natural” generalization of the celebrated Dirichlet prior. Among them the two parameter Poisson–Dirichlet prior certainly stands out in terms of mathematical tractability and interpretability of its predictive probabilities, which made it the natural candidate in a plethora of applications. Given a random sample of size n from an arbitrary Gibbs-type prior, we show that the corresponding predictive probabilities admit a large n approximation, with an error term vanishing as o(1/n), which maintains the same desirable features as the predictive probabilities of the two parameter Poisson–Dirichlet prior. Our result is illustrated through an extensive simulation study, which includes an application in the context of Bayesian nonparametric mixture modeling.

Inference in high dimensional parameter space poses many challenges. One of these is the possible use of saddlepoint approximations. Motivated by a recent use of the saddlepoint approximation to construct a conditional test, we argue that the precision is questionable. We illustrate this by an example giving a 50% relative error in the calculation of the p-value. A power study of the underlying test reveals a low power in many situations. As an alternative it is suggested to use the likelihood ratio test.

Motivated by a (seemingly previously unnoticed) result stating that d −dimensional distributions on $(0,\infty )^{d}$ are characterized by the collection of their min-linear projections, we introduce and study a notion of min-characteristic function (min-CF) of a random vector with strictly positive components. Unlike the related notion of max-characteristic function which has been studied recently, the existence of the min-CF does not hinge on any integrability conditions. It is itself a multivariate distribution function, which is continuous and concave, no matter which properties the initial distribution function has. We show the equivalence between convergence in distribution and pointwise convergence of min-CFs, and we also study the functional convergence of the min-CF of the empirical distribution function of a sample of independent and identically distributed random vectors. We provide some further insight into the structure of the set of min-CFs, and we conclude by showing how transforming the components of an arbitrary random vector by a suitable one-to-one transformation such as the exponential function allows the construction of a notion of min-CF for arbitrary random vectors.

Let T be the first time that the time-homogeneous jump-diffusion process X(t) leaves the interval (a, b). The jump size is assumed to be a positive constant. We derive exact formulas for E[Xk(T)] in special cases. For the general case, an approximate analytical expression can be obtained for E[Xk(T)]. This expression is precise when the jump size is small.