Subjective probability and the dfr-mixture closure theorem

It is well known that mixtures of DFR distributions are themselves DFR. The IFR class, on the other hand, is not closed under mixture, We present a simple new proof which gives insight into the result from a subjective stand-point.     

微博平台不同营销路径的效用探索——以互动效用为视角

社交媒体已经深刻地影响着企业与消费者的交互方式。以UGC互动效用为切入点,将品牌官方微博和个人认证微博分别作为研究对象,采用逐步回归方法分析品牌官方微博的影响路径,探究潜在消费者从感知博主信任度到产生行为反应的营销路径,同时比较分析品牌官方微博和个人认证微博的不同效用。结果表明：品牌官方微博博主感知可信度通过UGC互动效用显著正向影响未来行为,其中通过UGC社会效用产生的影响更显著;个人认证微博博主感知可信度通过UGC互动效用同时显著正向影响即时行为与未来行为,其中UGC社会效用在营销路径中发挥完全中介作用。企业开展微博营销活动时,要重视UGC的互动效用,积极发挥品牌官方微博和个人认证微博的不同效用。     

A generalized Pearson system useful in reliability analysis

In the present note, we study an extended class of Pearson system of distributions in the context of reliability. It is shown that the proposed class of models can be characterized by a relatioaship between the failure rate and the conditional moments. Further, we develop a procedure to identify an increasing (decreasing) failure rate model in the generalized Pearson system.     

Preventive replacement policies with products update announcements

Abstract

When we consider the improvement of the functional performances that are released by the new updates of the products, it is an interesting problem to revisit the existing replacement policies. For such a viewpoint, four replacement models with product update announcements, i.e., PUA for abbreviation, are given in this paper: Model 1, the unit is replaced at time T or at PUA over time T. Model 2, the unit is replaced at the Kth failure or at PUA over the Kth failure. By considering both time T and failure K, Models 3 and 4 are obtained based on the approaches of replacement first and last. We obtain the expected cost rates for four models and discuss analytically their optimal replacement policies Further, numerical examples are given when the time for PUA has an exponential distribution.     

Estimation of the marginal survival time in the presence of dependent competing risks using inverse probability of censoring weighted (IPCW) methods

In medical studies, there is interest in inferring the marginal distribution of a survival time subject to competing risks. The Kyushu Lipid Intervention Study (KLIS) was a clinical study for hypercholesterolemia, where pravastatin treatment was compared with conventional treatment. The primary endpoint was time to events of coronary heart disease (CHD). In this study, however, some subjects died from causes other than CHD or were censored due to loss to follow-up. Because the treatments were targeted to reduce CHD events, the investigators were interested in the effect of the treatment on CHD events in the absence of causes of death or events other than CHD. In this paper, we present a method for estimating treatment group-specific marginal survival curves of time-to-event data in the presence of dependent competing risks. The proposed method is a straightforward extension of the Inverse Probability of Censoring Weighted (IPCW) method to settings with more than one reason for censoring. The results of our analysis showed that the IPCW marginal incidence for CHD was almost the same as the lower bound for which subjects with competing events were assumed to be censored at the end of all follow-up. This result provided reassurance that the results in KLIS were robust to competing risks.     

Corrections and amendments

In the Competing risk analysis g_i(t) the failure rates h_i(t) and g_i(t) (as defined ) are, in general, not the same. However, of the survival times due to different causes are independent, then g_i (t) = h_i (t) this is a model studied by chiang (1961). In this note we have exhibited some counterexamples illustrating the relationships between g_i (t)= h_i (t) and the independence of survival times.     

Analysis of Gamma and Weibull lifetime data under a general censoring scheme and in the presence of covariates

We consider the problem of estimating the lifetime distributions of survival times subject to a general censoring scheme called “middle censoring”. The lifetimes are assumed to follow a parametric family of distributions, such as the Gamma or Weibull distributions, and is applied to cases when the lifetimes come with covariates affecting them. For any individual in the sample, there is an independent, random, censoring interval. We will observe the actual lifetime if the lifetime falls outside of this censoring interval, otherwise we only observe the interval of censoring. This censoring mechanism, which includes both right- and left-censoring, has been called “middle censoring” (see Jammalamadaka and Mangalam, 2003 Jammalamadaka, S. Rao, Mangalam, V. (2003). Nonparametric estimation for middle censored data. J. Nonparamet. Stat. 15(2):253–265.[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]). Maximum-likelihood estimation of the parameters as well as their large-sample properties are studied under this censoring scheme, including the case when covariates are available. We conclude with an application to a dataset from Environmental Economics dealing with ContingentValuation of natural resources.     

The godmother of gendered organizations: In celebration of the work of Joan Acker

Joan Acker can be considered the godmother of gendered organizations. In this paper, we reflect on the impact that Joan Acker's work has on our thinking and our careers as gender scholars in management and organization studies in Europe. First, we tell our personal stories of close encounters with Joan Acker. Second, we highlight what we consider to be two key contributions of Joan Acker. The first are the interrelated gendered processes regarding structure, culture, interaction and identity from her work in the early 1990s, the second the notion of inequality regimes from her later work on the intersections of gender, class and race. We then discuss how Acker's work has been influential in our research on gendered organizations, and in our teaching when we use it in our explanations of the functioning of gender in organizations to students, and in our work as advisors and consultants for organizations interested in equality, diversity and inclusion. Finally, we elaborate on new directions building on Acker's work, especially in current theorizing on gender and diversity in organizational change.     

Personal Project Content and Stress: Relations to Subjective Health and Depressive Mood

The aim of this study was to examine how personal project stress and stress related to different personal project contents are associated with subjective health and depressive mood among adults. Participants were 343 men and women (20–76 years old), who responded to the questionnaire including the Little’s Personal Project Analysis, and health and depression measures. As expected, high personal project stress was related to lower perceived general health, greater number of health complaints, and higher level of depressive mood. Further analysis showed that general health, health complaints, and depressive mood were predicted by stress related to specific personal project contents.