Survival Analysis For A Sequenced Clinical Trial With Covariates

In this paper we discuss the survival analysis for a clinical trial in which treatment categories and general prognostic data are realised at different stages during a patient's survival time. In the light of possible strategies for the parsimonious modelling of such data, a corresponding sequence of illustrative analyses is presented. Detailed results are given for a weighted least squares analysis and these generally agree with those obtained by maximum likelihood.     

How Provider Selection and Management Contribute to Successful Innovation Outsourcing: An Empirical Study at Siemens

It is becoming increasingly common to involve external technology providers in developing new technologies and new products. Two important phases involved in working with technology vendors are vendor selection and vendor management. Because for both steps theory development of key decision guidelines is still immature, we use detailed case studies of 31 innovation outsourcing projects at Siemens to develop grounded theory on provider selection criteria and on project management success drivers. A selection criterion often associated with successful outsourcing is the provider's “track record” or previous experience. Our cases suggest that there is no standard “track record” for success but that a “match” between the client firm's outsourcing motivation and the provider's strengths appears to be a necessary condition for a successful outsourcing collaboration. As to the second phase—managing the vendor—we identify a number of operational project success drivers. There seems to be no universal checklist, but the most important drivers seem to be contingent on the type of vendor chosen and on the maturity of the technology. We compare five provider types—universities, competitors, customers, start‐up companies, and component suppliers—and find that some success drivers are common to all providers, while others are relevant only for certain types of provider. Moreover, drivers in the case of a mature technology are more focused on successful transfer to manufacturing than on development itself. Our findings offer guidelines for innovation managers on how to select innovation providers and how to manage them during the project.     

How robust are tests for two independent samples?

Non-parametric procedures are sometimes in use even in cases where the corresponding parametric procedure is preferable. This is mainly due to the fact that in practical applications of statistical methods too much attention is paid to any violation of the normality assumption–normal distribution is, however, primarily supposed in order to easily derive the exact distribution of the statistic used within parametric approaches.     

康德定言命令的道德变革与实践困境

康德以纯粹理性形而上学为基础,强调善良意志和定言命令的实践理性价值.以定言命令为核心的道德形而上学实践理性排斥伦理学经验论,弘扬人的主体能动性,在西方伦理学引起了重大的道德哲学方向性转变.然而,定言命令具有形式化和僵化的普遍化特征,存在严重的形而上矛盾和现实困境,受到黑格尔等人的伦理学批判以及马克思主义唯物主义实践论的超越.     

Outlier detection in contingency tables using decomposable graphical models

For high-dimensional data, it is a tedious task to determine anomalies such as outliers. We present a novel outlier detection method for high-dimensional contingency tables. We use the class of decomposable graphical models to model the relationship among the variables of interest, which can be depicted by an undirected graph called the interaction graph. Given an interaction graph, we derive a closed-form expression of the likelihood ratio test (LRT) statistic and an exact distribution for efficient simulation of the test statistic. An observation is declared an outlier if it deviates significantly from the approximated distribution of the test statistic under the null hypothesis. We demonstrate the use of the LRT outlier detection framework on genetic data modeled by Chow–Liu trees.     

Testing the proportional odds assumption in multiply imputed ordinal longitudinal data

A popular choice when analyzing ordinal data is to consider the cumulative proportional odds model to relate the marginal probabilities of the ordinal outcome to a set of covariates. However, application of this model relies on the condition of identical cumulative odds ratios across the cut-offs of the ordinal outcome; the well-known proportional odds assumption. This paper focuses on the assessment of this assumption while accounting for repeated and missing data. In this respect, we develop a statistical method built on multiple imputation (MI) based on generalized estimating equations that allows to test the proportionality assumption under the missing at random setting. The performance of the proposed method is evaluated for two MI algorithms for incomplete longitudinal ordinal data. The impact of both MI methods is compared with respect to the type I error rate and the power for situations covering various numbers of categories of the ordinal outcome, sample sizes, rates of missingness, well-balanced and skewed data. The comparison of both MI methods with the complete-case analysis is also provided. We illustrate the use of the proposed methods on a quality of life data from a cancer clinical trial.     

英汉次谓语的语义对比研究

次谓语有描述性次谓语和结果性次谓语之分。从语义取向方面来看,英语描述性次谓语可以是主语取向的也可以是宾语取向的,结果性次谓语只能是宾语取向的;汉语中,描述性次谓语和结果性次谓语既可以是宾语取向的也可以是主语取向的。语义选择决定语类选择,充当英汉次谓语的词语虽有特例但一般是动态谓词。多个次谓语在一个句中共存时存在语义限制,那就是一个句子只能被限定一次,但是英汉多个次谓语在句中出现的顺序不一样。英汉次谓语都具有使句子表达生动、简洁、流畅的语义强势。     

A generalized ordered Probit model

Abstract

The ordered probit and logit models, based on the normal and logistic distributions, can yield biased and inconsistent estimators when the distributions are misspecified. A generalized ordered response model is introduced which can reduce the impact of distributional misspecification. An empirical exploration of various determinants of life satisfaction suggests possible benefits of allowing for diverse distributional characteristics. These improvements are confirmed using a Monte Carlo study to contrast the performance of the flexible parametric specifications to the probit and logit specifications.     

A proposal for handling ordinal categorical variables in co-inertia analysis

This paper is about the problem of the treatment of ordinal qualitative variables in co-inertia analysis. In the literature, there are different proposals based on the application of known statistical techniques to quantify ordinal variables. Here we propose to use a new procedure for the coding considering the empirical distributions of the variables involved in the analysis. We present an application to a real dataset, comparing the results obtained with the different kinds of quantification.