A longitudinal model for shapes through triangulation

AStA Advances in Statistical Analysis - It is known that the shapes of planar triangles can be represented by a set of points on the surface of the unit sphere. On the other hand, most of the...     

Construction of Simultaneous Confidence Intervals for Ratios of Means of Lognormal Distributions

For constructing simultaneous confidence intervals for ratios of means for lognormal distributions, two approaches using a two-step method of variance estimates recovery are proposed. The first approach proposes fiducial generalized confidence intervals (FGCIs) in the first step followed by the method of variance estimates recovery (MOVER) in the second step (FGCIs–MOVER). The second approach uses MOVER in the first and second steps (MOVER–MOVER). Performance of proposed approaches is compared with simultaneous fiducial generalized confidence intervals (SFGCIs). Monte Carlo simulation is used to evaluate the performance of these approaches in terms of coverage probability, average interval width, and time consumption.     

Bayesian prediction for progressively censored data from the Burr model

Received: August 14, 2000; revised version: April 23, 2001     

Bayesian Prediction for Progressively Type-II Censored Data from the Rayleigh Model

ABSTRACT

The Rayleigh distribution is proposed to be the underlying model from which observables are to be predicted by using Bayesian approach. Progressively Type-II censored data from the Rayleigh distribution is considered and the two-sample prediction technique is used. Numerical computations and a simulation are given to illustrate the performance of the procedures.     

Does Gender Diversity Affect Workplace Happiness for Academics? The Role of Diversity Management and Organizational Inclusion

Public Organization Review - The author investigated the relationship between gender diversity and organizational inclusion and moved forward to examine whether gender diversity, diversity...     

The use of simple reparameterizations to improve the efficiency of Markov chain Monte Carlo estimation for multilevel models with applications to discrete time survival models

Summary.  We consider the application of Markov chain Monte Carlo (MCMC) estimation methods to random-effects models and in particular the family of discrete time survival models. Survival models can be used in many situations in the medical and social sciences and we illustrate their use through two examples that differ in terms of both substantive area and data structure. A multilevel discrete time survival analysis involves expanding the data set so that the model can be cast as a standard multilevel binary response model. For such models it has been shown that MCMC methods have advantages in terms of reducing estimate bias. However, the data expansion results in very large data sets for which MCMC estimation is often slow and can produce chains that exhibit poor mixing. Any way of improving the mixing will result in both speeding up the methods and more confidence in the estimates that are produced. The MCMC methodological literature is full of alternative algorithms designed to improve mixing of chains and we describe three reparameterization techniques that are easy to implement in available software. We consider two examples of multilevel survival analysis: incidence of mastitis in dairy cattle and contraceptive use dynamics in Indonesia. For each application we show where the reparameterization techniques can be used and assess their performance.     

MINIMAX ESTIMATION OF A MULTIVARIATE NORMAL MEAN UNDER A CONVEX LOSS FUNCTION

Let X = (X₁, - X_p)prime; ˜ N_p (μ, Σ) where μ= (μ₁, -, μ_p)' and Σ= diag (Σ²₁, -, Σ²_p) are both unknown and p3. Let (n_i - 2) w_i/Σ²_i! X²_ni, independent. of w_i (I ≠ j = 1, -, p). Assume that (w₁, -, w_p) and X are independent. Define W = diag (w₁, -, w_p) and ¶ X ¶²_w= X'W^-1Q^-1W^-1X where Q = diag (q₁, -,n q_p), q_i > 0, i = 1, -, p. In this paper, the minimax estimator of Berger & Bock (1976), given by δ (X, W) = [I_p - r(X, W) ¶ X ¶^-2_w Q^-1W^-1] X, is shown to be minimax relative to the convex loss (δ - μ)'[αQ + (1 - α) Σ^-1] δ - μ)/C, where C =α tr (Σ) + (1 - α)p and 0 α 1, under certain conditions on r(X, W). This generalizes the above mentioned result of Berger & Bock.     

Study of Cases of Child Sexual Abuse Referred for Medico-Legal Examination in Cairo and Giza,Egypt,2007–2011

ABSTRACT

Child sexual abuse is a complex problem that results in detrimental effects on its victims. This study aimed to investigate the pattern of child sexual abuse in cases referred for medico-legal examination in Cairo and Giza governorates in the period between 2007–2011. The study included 813 cases of child sexual abuse. Female gender was more predominant than male gender (52.8%, 4.29 cases), and adolescents were the most frequent age group identified as victims of sexual abuse (43.8%, 356 cases). All perpetrators were male and most of them were persons outside the victims’ families (89.9%, 731 cases). It was recommended to teach and encourage children to tell their caregivers if they have been assaulted and to educate parents and caregivers on how to respond when the child discloses sexual abuse.