Dealing with excess of zeros in the statistical analysis of magnetic resonance imaging lesion count in multiple sclerosis

Lesion count observed on brain magnetic resonance imaging scan is a common end point in phase 2 clinical trials evaluating therapeutic treatment in relapsing remitting multiple sclerosis (MS). This paper compares the performances of Poisson, zero‐inflated poisson (ZIP), negative binomial (NB), and zero‐inflated NB (ZINB) mixed‐effects regression models in fitting lesion count data in a clinical trial evaluating the efficacy and safety of fingolimod in comparison with placebo, in MS. The NB and ZINB models prove to be superior to the Poisson and ZIP models. We discuss the advantages and limitations of zero‐inflated models in the context of MS treatment. Copyright © 2012 John Wiley & Sons, Ltd.     

Disability and dirty workers: stories of physical,social and moral taint

Returning to classics on dirty work and stigma, I offer another perspective on the difficulties that disabled people experience in employment. I claim that disabled workers with multiple sclerosis (MS) feel like ‘dirty workers’ not because of the work that they do, but because of their MS. Secondary analysis of phenomenological interview data revealed workers with MS feeling physical, social and moral taints normally associated with being a ‘dirty worker’ – but because of their MS-related impairments and disabilities. Two respondent stories are shared to illustrate this association.     

广告创意中的侧向思维—心理学原理在广告活动中的应用

广告创意中的侧向思维一般出现在创意者寻找表现广告主题的新颖方案的过程中。与广告主题之间有内在逻辑联系的局外信息,能在侧向思维过程中激发创意灵感,为解决创意难题提供了可能性。该种可能性转变为现实性的条件是创意者坚定不移地寻找创意方案,创意者有一定的智能水平。     

A proportional-hazards model for survival analysis and long-term survivors modeling: application to amyotrophic lateral sclerosis data

The majority of survival data are affected by explanatory variables. We develop a new regression model for survival data analysis. As an alternative to standard mixture models, another model is proposed to describe the eventual presence of a surviving fraction. The proposed models are based on the Marshall–Olkin extended generalized Gompertz distribution. A maximum-likelihood inference is presented in the presence of covariates and a censorship phenomenon. Explanatory variables are incorporated into the model through proportional-hazards to evaluate the effect of risk factors on overall survival under different assumptions. Parametric, semi-parametric, and non-parametric methods are applied to survival analysis of patients treated for amyotrophic lateral sclerosis. Interesting results about riluzole use and other treatment effects on patients'' survival have been obtained.     

老年脑梗死患者与颈动脉硬化关系的研究

目的研究老年脑梗死患者与颈动脉硬化的关系。方法采用彩色多普勒超声仪测定80例老年脑梗死患者的双侧颈动脉的脂质斑块形成情况。结果全部病历均有不同程度的颈动脉硬化,其中粥样斑块形成占87.5%,常见部位依次是颈动脉分叉处、颈总动脉和颈内动脉,受年龄增长及伴有高血压病和糖尿病等因素影响,导致患者硬化程度加重。结论颈动脉硬化是老年人脑梗死的重要原因,老年人颈动脉检查应进一步得到重视。     

A simple test for the treatment effect in clinical trials with a sequential parallel comparison design and negative binomial outcomes

In placebo‐controlled, double‐blinded, randomized clinical trials, the presence of placebo responders reduces the effect size for comparison of the active drug group with the placebo group. An attempt to resolve this problem is to use the sequential parallel comparison design (SPCD). Although there are SPCDs with dichotomous or continuous outcomes, an SPCD with negative binomial outcomes—with which investigators deal eg, in clinical trials involving multiple sclerosis, where the investigators are still concerned about the presence of placebo responders—has not yet been discussed. In this article, we propose a simple test for the treatment effect in clinical trials with an SPCD and negative binomial outcomes. Through simulations, we show that the analysis method achieves the nominal type I error rate and power, whereas the sample size calculation provides the sample size with adequate power accuracy.     

Simulation-Based Confidence Intervals for Functions With Complicated Derivatives

In many scientific problems, the quantity of interest is a function of parameters that index the model, and confidence intervals are constructed by applying the delta method. However, when the function of interest has complicated derivatives, this standard approach is unattractive and alternative algorithms are required. This article discusses a simple simulation-based algorithm for estimating the variance of a transformation, and demonstrates its simplicity and accuracy by applying it to several statistical problems.     

项目人力资源调度研究综述

通过有限元理论计算及既有桥动力性能测试，指出大准线既有简支T梁横向刚度不能满足线路扩能需要，需要进行加固。从机理上对影响桥跨动力性能的因素进行了分析，指明了加固的总体方向。利用MIDAS/Civil有限元软件，对不同加固方式进行计算，比较并确定了最优加固思路，最终给出了推荐方案：加宽梁两端上下横隔板各0.65 m，且对加宽部位施加横向预应力。理论及实测结果表明，加固方案合理可行。     

Using Social Media to Change the Narrative Around Chronic Illness

Chronic illness is a prevalent issue for many individuals. Various theoretical approaches have been employed in the psychotherapeutic treatment of chronic illness and the effects it has on the individual with the illness. These approaches frequently overlook the strengths of the person living with the illness as well as fail to address aspects of modern life such as social media use of the client and the influence it holds for those living with a chronic illness. This paper proposes the application of narrative therapy and social media use as a narrative therapeutic technique when treating those who suffer from chronic illness. A clinical vignette is used to illustrate possible applications of therapeutic techniques in conjunction with therapist-directed social media use. Implications for clinical practice and limitations are discussed.     

On the application of statistical learning approaches to construct inverse probability weights in marginal structural Cox models: Hedging against weight-model misspecification

The marginal structural Cox model (MSCM) estimates can be highly sensitive to weight-model misspecification. We assess the performance of various popular statistical learners, such as LASSO, support vector machines, CART, bagged CART, and boosted CART, in estimating MSCM weights. When weight-models are misspecified, we find that the weights computed from boosted CART generally lead to less MSE and better coverage for the MSCM estimates. This study is motivated by the investigation of the impact of beta-interferon treatment on disability progression in subjects with multiple sclerosis from British Columbia, Canada (1995–2008).