Goodness-of-Fit Test and Parameter Estimation for a Proportional Odds Model of Random Censorship

Censored data arise naturally in a number of fields, particularly in problems of reliability and survival analysis. There are several types of censoring, in this article, we will confine ourselves to the right randomly censoring type. Recently, Ahmadi et al. (2010 Ahmadi , J. , Doostparast , M. , Parsian , A. ( 2010 ). Bayes estimation based on random censored data for some life time models under symmetric and asymmetric loss functions . Communcations in Statistics-Theory and Methods , 39 : 3058 – 3071 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) considered the problem of estimating unknown parameters in a general framework based on the right randomly censored data. They assumed that the survival function of the censoring time is free of the unknown parameter. This assumption is sometimes inappropriate. In such cases, a proportional odds (PO) model may be more appropriate (Lam and Leung, 2001 Lam , K. F. , Leung , T. L. ( 2001 ). Marginal likelihood estimation for proportional odds models with right censored data . Lifetime Data Analysis 7 : 39 – 54 .[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Under this model, in this article, point and interval estimations for the unknown parameters are obtained. Since it is important to check the adequacy of models upon which inferences are based (Lawless, 2003 Lawless , J. F. (2003). Statistical Models and Methods for Lifetime Data. , 2nd ed. New York : John Wiley & Sons. [Google Scholar], p. 465), two new goodness-of-fit tests for PO model based on right randomly censored data are proposed. The proposed procedures are applied to two real data sets due to Smith (2002 Smith , P. J. ( 2002 ). Analysis of Failure and Survival Data . London : Chapman & Hall, CRC . [Google Scholar]). A Monte Carlo simulation study is conducted to carry out the behavior of the estimators obtained.     

The Feminist “Quarantine” on Hijab: A Study of Its Two Mutually Exclusive Sets of Meanings

The discourse on feminism is sharply polarized between those who regard hijab as essentially debilitating and those who see it as an enabling tool for dignity, self-worth and freedom. This article will discuss both the negative and positive associations of hijab and point out ways it is used by Muslim women for liberatory ends. It will go against the grain of a common argument that hijab equates seclusion and constraints on women’s participation in public life hence it is inherently oppressive. I will argue that hijab can potentially be used for diametrically opposite purposes. While acknowledging the fact that the Islamic dress code for women can be misused by patriarchal power systems as well as by women themselves, I will put forth arguments against dismissive and uncritical criticism of hijab.     

Freedom and struggling openly in psychotherapy: A qualitative inquiry with LGBQ young adults from religious families

Lesbian, gay, bisexual, and queer (LGBQ) young people from religious families are at increased risk of family rejection, poor mental health outcomes, and are overrepresented in mental health services. This article describes a two‐part qualitative study aimed at exploring the experiences of LGBQ young adults from religious families in psychotherapy, identifying positive and negative psychotherapy experiences, and understanding the influence of family and religion on the psychotherapy experience. Data were collected through a web‐based survey (n = 77) and interviews (n = 7) with LGBQ young adults (ages 18–25) from religious families. The study followed an interpretative phenomenological approach. Integrated results found often invisible, relational therapy processes, and religious discourses as significant to LGBQ young people who seek psychotherapy. Implications for future research, effective systemic family therapy practices with LGBQ young people from religious families, and a critique on ethical and legal limits of confidentiality with policy implications are outlined.     

Value of and Interaction between Production Postponement and Information Sharing Strategies for Supply Chain Firms

We analyze the value of and interaction between production postponement and information sharing, which are two distinct strategies to reduce manufacturers’ uncertainty about demand. In both single‐level and two‐level supply chains, from the manufacturer's perspective, while information sharing is always valuable, production postponement can sometimes be detrimental. Furthermore, the value of production postponement is not merely driven by savings in inventory holding cost as postponement enables the manufacturer to avoid both excess and shortfall in production. We find that production postponement and information sharing strategies may substitute, complement, or conflict with each other, depending on the extent of the increase in the unit production cost when production is postponed. In a two‐level supply chain, from the retailer's perspective, information sharing and production postponement can be beneficial or detrimental. When information sharing is beneficial to the retailer, the retailer always shares her demand information with the manufacturer voluntarily. In addition, this voluntary information sharing is truthful because inflated or deflated demand information hurts the retailer through a higher wholesale price or a stock‐out. However, the retailer never shares her demand information voluntarily if the manufacturer has already adopted production postponement because production postponement and information sharing strategies always conflict with each other. Even when the retailer does not benefit from information sharing, we show that the manufacturer can always design an incentive mechanism to induce the retailer to share the demand information, irrespective of whether the manufacturer has already implemented production postponement or not. The above findings underscore the need for a careful assessment of demand uncertainty‐reduction strategies before the supply chain players embark upon them.     

Citizens’ Initiatives for Crisis Management and the Use of Social Media: An Analysis of COVID-19 Crisis in Bangladesh

Public Organization Review - This study analyses different social media-based citizens’ initiatives taken during the COVID-19 crisis in Bangladesh. By applying netnography on various Facebook...     

Forging a Brazilian Islam: Muslim Converts Negotiating Identity in São Paulo

Converts form a growing portion of the Muslim community in São Paulo, Brazil. Often introduced to Islam through media representations, they turn to religion for a variety of reasons, including the desire to search for spiritual truth. This article will examine questions of identity that arise during the process of religious conversion, using data gathered from extensive fieldwork. Specifically, it will analyze how male converts view the place of Islam within the context of Brazilian society and how they reimagine concepts of personal identity through religious conversion. The study suggests that converts hold diverse points of view regarding the development of their spiritual identity, emphasizing both the challenges and benefits of being Muslim and practicing Islam in Brazil.     

Median rankit control chart by the quantile approach

It is desirable that the data for a statistical control chart be normally distributed. However, if the data are not normal, then a transformation can be used, e.g. Box-Cox transformations, to produce a suitable control chart. In this paper we will discuss a quantile approach to produce a control chart and to estimate median rankit for various non-normal distributions. We will also provide examples of logistic data to indicate how a quantile approach could be used to construct a control chart for a non-normal distribution using a median rankit.     

Improved Simulation Techniques for First Exit Time of Neural Diffusion Models

We consider the fixed and exponential time-stepping Euler algorithms, with boundary tests, to calculate the mean first exit times (MFET) of two one-dimensional neural diffusion models, represented by the Ornstein–Uhlenbeck (OU) process and a stochastic space-clamped FitzHugh–Nagumo (FHN) system. The numerical methods are described and the convergence rates for the MFET analyzed. A boundary test improves the rate of convergence from order one-half to order 1. We show how to apply the multi-level Monte Carlo (MLMC) method to an Euler time-stepping method with boundary test and this improves the Monte Carlo computation of the MFET.     

Testing equality of two normal means using combined samples of paired and unpaired data

A test for equality of two normal means when the data consist of both paired and unpaired observations is proposed. The proposed test is compared with two other standard methods known in the literature with respect to the type I error rate and power using simulation results.