Browsing Research Articles (Statistics) by UP Author "Arashi, Mohammad"

Browsing Research Articles (Statistics) by UP Author "Arashi, Mohammad"

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  • Ferreira, Johannes Theodorus; Bekker, Andriette, 1958-; Arashi, Mohammad (National Statistical Institute of Portugal, 2020-07)
    This paper paves the way when the assumption of normality is challenged within the wireless communications systems arena. Innovative results pertaining to the distributions of quadratic forms and their associated eigenvalue ...
  • Van Niekerk, Janet; Bekker, Andriette, 1958-; Arashi, Mohammad (Sage, 2019-12)
    Real phenomena often leads to challenges in data. One of these is outliers or influential values. Especially in a small sample, these values can have a major influence on the modeling process. In the beta regression ...
  • Bekker, Andriette, 1958-; Roux, Jacobus J.J.; Ehlers, Rene; Arashi, Mohammad (Routledge, 2011-11)
    In this article, the bimatrix variate beta Type IV distribution is derived from independent Wishart distributed matrix variables. We explore specific properties of this distribution which is then used to derive the exact ...
  • Ferreira, Johannes Theodorus; Bekker, Andriette, 1958-; Arashi, Mohammad (South African Statistical Association, 2016)
    This paper enriches the existing literature of bivariate noncentral distributions by proposing bivariate noncentral generalised chi-square and F distributions via the employment of the compounding method with Poisson ...
  • Bekker, Andriette, 1958-; Roux, Jacobus J.J.; Ehlers, Rene; Arashi, Mohammad (Elsevier, 2012-03)
    The product moments of existing and new noncentral bimatrix variate beta distributions with bounded domain are derived. From these, exact expressions for the distributions of statistics are obtained by using the Mellin ...
  • Van Niekerk, Janet; Bekker, Andriette, 1958-; Arashi, Mohammad; De Waal, Duan J.31cca2cb-0f0b-4ea7-a9c1-9711569804a7 (South African Statistical Association, 2016)
    The problem of estimation within the matrix variate elliptical model is addressed. In this paper a subjective Bayesian approach is followed to derive new estimators for the parameters of the matrix variate elliptical ...
  • Bekker, Andriette, 1958-; Roux, Jacobus J.J.; Arashi, Mohammad (Elsevier, 2011-03)
    The study of the noncentral matrix variate beta type distributions has been sidelined because the final expressions for the densities depend on an integral that has not been resolved in an explicit way. We derive an exact ...
  • Nakale, S.; Coetsee, Judy; Arashi, Mohammad; Bekker, Andriette, 1958- (South African Statistical Association, 2013-11)
    In this paper we investigate the finite sample risk performance of feasible generalised least squares estimators applied in models with serially correlated error terms. The risk functions of the ordinary least squares, ...
  • Arashi, Mohammad; Bekker, Andriette, 1958-; Loots, Mattheus Theodor; Roux, Jacobus J.J. (Routledge, 2015-04)
    In this paper, an integral representation for the density of a matrix variate quaternion elliptical distribution is proposed. To this end, a weight func- tion is used, based on the inverse Laplace transform of a function ...
  • Arashi, Mohammad; Nagar, Priyanka; Bekker, Andriette, 1958- (MDPI Publishing, 2020-05-26)
    South Africa has great potential for considering wind energy as an alternative resource. The climatology allows for significant wind energy production. An accurate joint description of the wind speed (linear) and wind ...
  • Bekker, Andriette, 1958-; Arashi, Mohammad; Ferreira, Johannes Theodorus (Taylor and Francis, 2019)
    In this paper a bivariate gamma type distribution emanating from the diagonal elements of an inverse Wishart type distribution is developed; which in turn originates from the complex matrix variate elliptical class. From ...
  • Arashi, Mohammad; Bekker, Andriette, 1958-; Ratnaparkhi, M. (South African Statistical Association, 2014-09)
    Form-invariance is the most practical and desired property of weighted distributions. Weighted distributions commonly arise as univariate probability models in many fields of applications, for example, survival data analysis ...
  • Makgai, S.L.; Bekker, Andriette, 1958-; Ferreira, Johannes Theodorus; Arashi, Mohammad (South African Statistical Association, 2017)
    In this paper, we propose new results on a beta-Pareto class. This extension evolved by using newly proposed class of beta distributions as generator distributions (F (x)) within the generator-parent approach: H (x) = F ...
  • Ferreira, Johannes Theodorus; Bekker, Andriette, 1958-; Arashi, Mohammad (National Statistical Institute of Portugal, 2016-10)
    The Rayleigh distribution, serving as a special case of the Weibull distribution, is known to have wide applications in survival analysis, reliability theory and commu- nication engineering. In this paper, Bayesian ...
  • Loots, Mattheus Theodor; Bekker, Andriette, 1958-; Arashi, Mohammad; Roux, Jacobus J.J. (Taylor & Francis, 2013)
    For the first time, the matrix-variate quaternion normal and quaternion Wishart distributions are derived from first principles, i.e. from their real counterparts, exposing the relations between their respective densities and ...
  • Nakale, S.; Kleyn, Judy; Arashi, Mohammad; Bekker, Andriette, 1958- (South African Statistical Association, 2015-03)
    The risk performances, under the symmetric squared error loss function, of the estimators of the regression coefficients after a preliminary test for serial correlation have been widely investigated in the literature. ...
  • Kleyn, Judy; Arashi, Mohammad; Bekker, Andriette; Millard, Sollie M. (Routledge, 2017-01)
    In this article, we consider the multiple regression model in the presence of multicollinearity and study the performance of the preliminary test estimator (PTE) both analytically and computationally, when it is a priori ...
  • Van Niekerk, Janet; Bekker, Andriette, 1958-; Arashi, Mohammad; Roux, Jacobus J.J. (Taylor and Francis, 2015-09)
    For the multivariate elliptical model subjective Bayesian estimators of the location vector and some functions of the characteristic matrix with the normal-inverse Wishart and the normal-Wishart as prior, respectively, are ...
  • Salehi, Mahdi; Arashi, Mohammad; Bekker, Andriette, 1958-; Ferreira, Johannes Theodorus; Chen, Ding-Geng (Din); Esmaeili, Foad; Frances, Motala (Frontiers Media, 2020-01)
    The purpose of this paper is to introduce a useful online interactive dashboard (https://mahdisalehi.shinyapps.io/Covid19Dashboard/) that visualize and follow confirmed cases of COVID-19 in real-time. The dashboard was ...
  • Naderi, Mehrdad; Bekker, Andriette, 1958-; Arashi, Mohammad; Jamalizadeh, Ahad (Public Library of Science, 2020-04-09)
    This paper introduces a new family of matrix variate distributions based on the mean-mixture of normal (MMN) models. The properties of the new matrix variate family, namely stochastic representation, moments and ...