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This paper considers Importance Sampling (IS) for the estimation of tail risks of a loss defined in terms of a sophisticated object such as a machine learning feature map or a mixed integer linear optimisation formulation. Assuming only…

Risk Management · Quantitative Finance 2021-06-21 Anand Deo , Karthyek Murthy

Asmussen and Lehtomaa [Distinguishing log-concavity from heavy tails. Risks 5(10), 2017] introduced an interesting function $g$ which is able to distinguish between log-convex and log-concave tail behaviour of distributions, and proposed a…

Methodology · Statistics 2023-07-25 Toshiya Iwashita , Bernhard Klar

A notoriously difficult challenge in extreme value theory is the choice of the number $k\ll n$, where $n$ is the total sample size, of extreme data points to consider for inference of tail quantities. Existing theoretical guarantees for…

Other Statistics · Statistics 2025-05-30 Johannes Lederer , Anne Sabourin , Mahsa Taheri

This article is devoted to the study of tail index estimation based on i.i.d. multivariate observations, drawn from a standard heavy-tailed distribution, i.e. of which 1-d Pareto-like marginals share the same tail index. A multivariate…

Statistics Theory · Mathematics 2014-04-10 Stéphan Clémençon , Antoine Dematteo

We provide exact asymptotics for the tail probabilities $\mathbb{P} \{S_{n,r} > x\}$ as $x \to \infty$, for fix $n$, where $S_{n,r}$ is the $r$-trimmed partial sum of i.i.d. St. Petersburg random variables. In particular, we prove that…

Probability · Mathematics 2015-07-13 István Berkes , László Györfi , Péter Kevei

Adaptive importance sampling (AIS) algorithms are widely used to approximate expectations with respect to complicated target probability distributions. When the target has heavy tails, existing AIS algorithms can provide inconsistent…

Computation · Statistics 2023-10-26 Thomas Guilmeau , Nicola Branchini , Emilie Chouzenoux , Víctor Elvira

This paper provides an introductory overview of how one may employ importance sampling effectively as a tool for solving stochastic optimization formulations incorporating tail risk measures such as Conditional Value-at-Risk. Approximating…

Risk Management · Quantitative Finance 2023-07-11 Anand Deo , Karthyek Murthy

We consider estimation of the extreme value index and extreme quantiles for heavy-tailed data that are right-censored. We study a general procedure of removing low importance observations in tail estimators. This trimming procedure is…

Statistics Theory · Mathematics 2021-05-13 Martin Bladt , Hansjoerg Albrecher , Jan Beirlant

On the basis of Nelson-Aalen nonparametric estimator of the cumulative distribution function, we provide a weak approximation to tail product-limit process for randomly right-censored heavy-tailed data. In this context, a new consistent…

Statistics Theory · Mathematics 2016-07-25 Brahim Brahimi , Djamel Meraghni , Abdelhakim Necir

Modeling and understanding multivariate extreme events is challenging, but of great importance in various applications - e.g. in biostatistics, climatology, and finance. The separating Hill estimator can be used in estimating the extreme…

Statistics Theory · Mathematics 2016-01-13 Matias Heikkilä , Yves Dominicy , Pauliina Ilmonen

We introduce a new type of estimator for the spectral tail process of a regularly varying time series. The approach is based on a characterizing invariance property of the spectral tail process, which is incorporated into the new estimator…

Statistics Theory · Mathematics 2021-03-16 Holger Drees , Anja Janßen , Sebastian Neblung

By introducing a weight function into the density power divergence, we develop a new class of robust and smooth estimators for the tail index of Pareto-type distributions, offering improved efficiency in the presence of outliers. These…

Statistics Theory · Mathematics 2025-07-25 Saida Mancer , Abdelhakim Necir , Djamel Meraghni

In this paper we establish the error rate of first order asymptotic approximation for the tail probability of sums of log-elliptical risks. Our approach is motivated by extreme value theory which allows us to impose only some weak…

Probability · Mathematics 2014-12-12 D. Kortschak , E. Hashorva

It was shown that when one disposes of a parametric information of the truncation distribution, the semiparametric estimator of the distribution function for truncated data (Wang, 1989) is more efficient than the nonparametric one. On the…

Statistics Theory · Mathematics 2021-06-03 Saida Mancer , Abdelhakim Necir , Souad Benchaira

Standard statistical analysis is unable to provide reliable confidence intervals on expectation values of probability distributions that do not satisfy the conditions of the central limit theorem. We present a regression-based estimator of…

Data Analysis, Statistics and Probability · Physics 2019-06-24 Pablo Lopez Rios , Gareth J. Conduit

Asymptotic expansions are derived for the tail distribution of the product of two correlated normal random variables with non-zero means and arbitrary variances, and more generally the sum of independent copies of such random variables.…

Probability · Mathematics 2025-05-27 Robert E. Gaunt , Zixin Ye

We derive in this article the exact non-asymptotical exponential and power estimates for self-normalized sums of centered independent random variables (r.v.) under natural norming. We will use also the theory of the so-called Grand Lebesgue…

Probability · Mathematics 2018-09-25 E. Ostrovsky , L. Sirota

Recently, the concept of tail dependence has been discussed in financial applications related to market or credit risk. The multivariate extreme value theory is a proper tool to measure and model dependence, for example, of large loss…

Applications · Statistics 2011-09-27 Marta Ferreira

We establish new tail estimates for order statistics and for the Euclidean norms of projections of an isotropic log-concave random vector. More generally, we prove tail estimates for the norms of projections of sums of independent…

We re-examine a lower-tail upper bound for the random variable $$X=\prod_{i=1}^{\infty}\min\left\{\sum_{k=1}^iE_k,1\right\},$$ where $E_1,E_2,\ldots\stackrel{iid}\sim\text{Exp}(1)$. This bound has found use in root-finding and seed-finding…

Probability · Mathematics 2019-05-21 Sam Justice , N. D. Shyamalkumar