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Journal ArticleDOI

A unified view on skewed distributions arising from selections

TL;DR: In this paper, a new definition of a selection distribution was proposed that encompasses many existing families of multivariate skewed distributions, such as the skew-normal and skew-elliptical distributions, and several methods of constructing selection distributions based on linear and nonlinear selection mechanisms.
Abstract: Parametric families of multivariate nonnormal distributions have received considerable attention in the past few decades. The authors propose a new definition of a selection distribution that encompasses many existing families of multivariate skewed distributions. Their work is motivated by examples that involve various forms of selection mechanisms and lead to skewed distributions. They give the main prop erties of selection distributions and show how various families of multivariate skewed distributions, such as the skew-normal and skew-elliptical distributions, arise as special cases. The authors further introduce several methods of constructing selection distributions based on linear and nonlinear selection mechanisms. Une perspective integree des lois asymetriques issues de processus de selection Resume: Les familles param6triques de lois multivari6es non gaussiennes ont suscite beaucoup d'int6ret depuis quelques decennies. Les auteurs proposent une nouvelle definition du concept de loi de selection qui englobe plusieurs familles connues de lois asymetriques multivari6es. Leurs travaux sont motives par diverses situations faisant intervenir des mecanismes de selection et conduisant 'a des lois asymetriques. Ils mentionnent les principales propri6t6s des lois de selection et montrent comment diverses familles de lois asymetriques multivariees telles que les lois asymetriques normales ou elliptiques emergent comme cas particuliers. Les auteurs presentent en outre plusieurs methodes de construction de lois de selection fondees sur des mecanismes lin6aires ou non lineaires.
Citations
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Book
01 Dec 2013
TL;DR: This comprehensive treatment, blending theory and practice, will be the standard resource for statisticians and applied researchers, and Assuming only basic knowledge of (non-measure-theoretic) probability and statistical inference, the book is accessible to the wide range of researchers who use statistical modelling techniques.
Abstract: Preface 1. Modulation of symmetric densities 2. The skew-normal distribution: probability 3. The skew-normal distribution: statistics 4. Heavy and adaptive tails 5. The multivariate skew-normal distribution 6. Skew-elliptical distributions 7. Further extensions and other directions 8. Application-oriented work Appendices References.

547 citations

Posted Content
TL;DR: In this article, a technique for introducing skewness or kurtosis into a symmetric or other distribution is proposed, based on a "transmutation map" which is the functional composition of the cumulative distribution function of one distribution with the inverse cumulative distribution (quantile) function of another.
Abstract: Motivated by the need for parametric families of rich and yet tractable distributions in financial mathematics, both in pricing and risk management settings, but also considering wider statistical applications, we investigate a novel technique for introducing skewness or kurtosis into a symmetric or other distribution. We use a "transmutation" map, which is the functional composition of the cumulative distribution function of one distribution with the inverse cumulative distribution (quantile) function of another. In contrast to the Gram-Charlier approach, this is done without resorting to an asymptotic expansion, and so avoids the pathologies that are often associated with it. Examples of parametric distributions that we can generate in this way include the skew-uniform, skew-exponential, skew-normal, and skew-kurtotic-normal.

348 citations


Additional excerpts

  • ...In Section 4 we conclude....

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Journal ArticleDOI
TL;DR: A systematic classification of the existing skew symmetric distributions into four types is presented, thereby clarifying their close relationships and aiding in understanding the link between some of the proposed expectation-maximization based algorithms for the computation of the maximum likelihood estimates of the parameters of the models.
Abstract: Finite mixtures of skew distributions have emerged as an effective tool in modelling heterogeneous data with asymmetric features. With various proposals appearing rapidly in the recent years, which are similar but not identical, the connection between them and their relative performance becomes rather unclear. This paper aims to provide a concise overview of these developments by presenting a systematic classification of the existing skew symmetric distributions into four types, thereby clarifying their close relationships. This also aids in understanding the link between some of the proposed expectation-maximization based algorithms for the computation of the maximum likelihood estimates of the parameters of the models. The final part of this paper presents an illustration of the performance of these mixture models in clustering a real dataset, relative to other non-elliptically contoured clustering methods and associated algorithms for their implementation.

191 citations


Cites background from "A unified view on skewed distributi..."

  • ...They include the FUST distribution and other subclasses of it, as well as the generalized form of the t-distribution put forward by Arellano-Valle et al. (2006), known as the selection t-distribution....

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Journal ArticleDOI
TL;DR: Some simulation studies are presented to show the advantage of this flexible class of probability distributions in clustering heterogeneous data and that the maximum likelihood estimates based on the EM-type algorithm do provide good asymptotic properties.

141 citations

Journal ArticleDOI
TL;DR: The paper shows that the market model is non-linear in general and that the sensitivity of asset returns to return on the market portfolio is not the same as the conventional beta, although this measure does arise in special cases.
Abstract: The returns on most financial assets exhibit kurtosis and many also have probability distributions that possess skewness as well. In this paper a general multivariate model for the probability distribution of assets returns, which incorporates both kurtosis and skewness, is described. It is based on the multivariate extended skew-Student-t distribution. Salient features of the distribution are described and these are applied to the task of asset pricing. The paper shows that the market model is non-linear in general and that the sensitivity of asset returns to return on the market portfolio is not the same as the conventional beta, although this measure does arise in special cases. It is shown that the variance of asset returns is time varying and depends on the squared deviation of market portfolio return from its location parameter. The first order conditions for portfolio selection are described. Expected utility maximisers will select portfolios from an efficient surface, which is an analogue of the familiar mean-variance frontier, and which may be implemented using quadratic programming.

122 citations


Cites background from "A unified view on skewed distributi..."

  • ...…publication of initial papers by Branco and Dey (2001), Azzalini and Capitanio (2003) and Sahu et al. (2003) has been followed by articles by several authors including Arellano-Valle and Genton (2005), Arellano-Valle et al. (2006), Arrellano-Valle and Azzalini (2006) and Azzalini and Genton (2008)....

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References
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Journal ArticleDOI
TL;DR: In this article, the bias that results from using non-randomly selected samples to estimate behavioral relationships as an ordinary specification error or "omitted variables" bias is discussed, and the asymptotic distribution of the estimator is derived.
Abstract: Sample selection bias as a specification error This paper discusses the bias that results from using non-randomly selected samples to estimate behavioral relationships as an ordinary specification error or «omitted variables» bias. A simple consistent two stage estimator is considered that enables analysts to utilize simple regression methods to estimate behavioral functions by least squares methods. The asymptotic distribution of the estimator is derived.

23,995 citations

Book
01 Jan 1994
TL;DR: Continuous Distributions (General) Normal Distributions Lognormal Distributions Inverse Gaussian (Wald) Distributions Cauchy Distribution Gamma Distributions Chi-Square Distributions Including Chi and Rayleigh Exponential Distributions Pareto Distributions Weibull Distributions Abbreviations Indexes
Abstract: Continuous Distributions (General) Normal Distributions Lognormal Distributions Inverse Gaussian (Wald) Distributions Cauchy Distribution Gamma Distributions Chi-Square Distributions Including Chi and Rayleigh Exponential Distributions Pareto Distributions Weibull Distributions Abbreviations Indexes

7,270 citations

Journal Article
TL;DR: In this paper, a nouvelle classe de fonctions de densite dependant du parametre de forme λ, telles que λ=0 corresponde a la densite normale standard.
Abstract: On introduit une nouvelle classe de fonctions de densite dependant du parametre de forme λ, telles que λ=0 corresponde a la densite normale standard

2,470 citations


"A unified view on skewed distributi..." refers background or methods or result in this paper

  • ...Another closed skew-normal distribution, which was introduced in Arellano-Valle & Azzalini (2006), follows also as a FUSN when ∆ = AΩU and ΩV = Ψ + AΩUA in (12)....

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  • ...The special case of the multivariate skew-t distribution that follows when G is the IG(ν/2, ν/2) distribution is studied in Arellano-Valle & Azzalini (2006)....

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  • ...Finally, we note that this approach was simply the starting point for Azzalini (1985)....

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  • ...If in additionp = 1, then (25) reduces to the pdf of the seminal univariate skew-normal distribution of Azzalini (1985, 1986); see also Gupta & Chen (2004) for a slightly different definition of a multivariate skewnormal distribution....

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  • ...1) can be used; see also Arellano-Valle & Genton (2005) and Arellano-Valle & Azzalini (2006) for more details on similar results....

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Journal ArticleDOI
TL;DR: In this article, a multivariate parametric family such that the marginal densities are scalar skew-normal is introduced, and its properties are studied with special emphasis on the bivariate case.
Abstract: SUMMARY The paper extends earlier work on the so-called skew-normal distribution, a family of distributions including the normal, but with an extra parameter to regulate skewness. The present work introduces a multivariate parametric family such that the marginal densities are scalar skew-normal, and studies its properties, with special emphasis on the bivariate case.

1,478 citations

Journal ArticleDOI
TL;DR: In this paper, a fairly general procedure is studied to perturb a multivariate density satisfying a weak form of multivariate symmetry, and to generate a whole set of non-symmetric densities.
Abstract: Summary. A fairly general procedure is studied to perturb a multivariate density satisfying a weak form of multivariate symmetry, and to generate a whole set of non-symmetric densities. The approach is sufficiently general to encompass some recent proposals in the literature, variously related to the skew normal distribution. The special case of skew elliptical densities is examined in detail, establishing connections with existing similar work. The final part of the paper specializes further to a form of multivariate skew t-density. Likelihood inference for this distribution is examined, and it is illustrated with numerical examples.

1,215 citations


"A unified view on skewed distributi..." refers background or methods or result in this paper

  • ...A fundamental property of all the selection distributions satisfyingP(U ∈ C) = 1/2 has been mentioned extensively in the literature, see, e.g., Azzalini (2005), Azzalini & Capitanio (2003), Genton (2005), Genton & Loperfido (2005), Wang, Boyer & Genton (2004b) for recent accounts....

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  • ...In particular, ifU is a random vector in theC-class, thenFU(0) = 2−q and (28) yields fX(x) = 2 qfV(x)FT(w(x)), (29) which is an extension of a similar result given by Azzalini & Capitanio (1999, 2003)....

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  • ...…is discussed in Azzalini & Capitanio (2003), who have shown that they are equivalent in many important cases, like the skew-t(ST) distribution studied by Branco & Dey (2001) and Azzalini & Capitanio (2003), and extended forq > 1 in Arellano-Valle & Azzalini (2006) as a member ofSUE distributions....

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  • ...The pdf of a skew-symmetric distribution based on (2) then takes the form fX(x) = 2fV(x)π(x), (23) which is similar to the formulation in Azzalini & Capitanio (2003) except for a different but equivalent representation ofπ(x)....

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  • ...It is currently the subject of vigorous research efforts and recent advances on this topic include work by Azzalini (2005), Azzalini & Capitanio (1999, 2003), DiCiccio & Monti (2004), Ma, Genton & Tsiatis (2005), Ma & Hart (2006), Pewsey (2000, 2006), and Sartori (2006)....

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