Partial orders with respect to continuous covariates and tests for the proportional hazards model

Several omnibus tests of the proportional hazards assumption have been proposed in the literature. In the two-sample case, tests have also been developed against ordered alternatives like monotone hazard ratio and monotone ratio of cumulative hazards. Here we propose a natural extension of these partial orders to the case of continuous and potentially time varying covariates, and develop tests for the proportional hazards assumption against such ordered alternatives. The work is motivated by applications in biomedicine and economics where covariate effects often decay over lifetime. The proposed tests do not make restrictive assumptions on the underlying regression model, and are applicable in the presence of time varying covariates, multiple covariates and frailty. Small sample performance and an application to real data highlight the use of the framework and methodology to identify and model the nature of departures from proportionality.     

简论李觏的土地思想

李觏是北宋中期重要的思想家,在李觏的整个思想体系中,经济思想占有很重要的地位。李觏非常重视土地问题,土地思想是李觏经济思想的核心。针对当时土地兼并日益激烈引起的社会危害,李觏也提出了关于土地问题的看法。他的土地思想经历了前后两个时期,前期主要从分配角度分析,主张平土均田。后期主要从生产角度批判土地兼并。李觏提出了"平土均田"、"井田制"、"农业劳动力"、"尽地力、广垦辟"、"限田"等抑制土地兼并,发展农业,保护农民利益的思想。     

我国商业银行客户忠诚度研究

随着银行业竞争的日益激烈,提高客户忠诚度已经成为决定银行盈利能力的关键。本文通过分析影响我国银行客户忠诚度的因素,建立了客户忠诚度及其影响因素之间的结构方程模型,并采用PLS方法对模型的参数进行估计。在此基础上,基于某商业银行的实际调查数据给出了一个算例,对计算的结果进行了分析,并提出了相应的对策建议。     

经典最小二乘法同时测定铀矿石中铀和钍

文章介绍了用偶氮胂Ⅲ作为显色剂，在8mol／IHCL介质中同时测定铀矿石中铀和钍的一种新方法。此法测钍的灵敏度达10^5、铀的灵敏度达10^4，均与文献相符。此法具有灵敏度高、选择性好的特点。     

用偏导数法求解一类二元函数方程

给出了形如f（w（xy））=R（f（x）f（y））的二元函数方程可微解的偏导数求法，将此类二元函数方程的求解归结为一阶常微分方程的求解问题     

Comparison of the Polar Decision Rules for Various Types of Distributions

We focus on the dichotomous choice model, which goes back as far as Condorcet (1785; Essai sur l'application de l'analyse a la probabilité des décisions rendues a la pluralité des voix, Paris). A group of experts is required to select one of two alternatives, of which exactly one is regarded as correct. The alternatives may be related to a wide variety of areas. A decision rule translates the individual opinions of the members into a group decision. A decision rule is optimal if it maximizes the probability of the group to make a correct choice. In this paper we assume the correctness probabilities of the experts to be independent random variables, selected from some given distribution. Moreover, the ranking of the members in the team is (at least partly) known. Thus, one can follow rules based on this ranking. The polar different rules are the expert and the majority rules. The probabilities of the two polar rules being optimal were compared in a series of papers. The main purpose of this paper is to outline the results, providing exact formulas or estimates for these probabilities. We consider a variety of distributions and show that for all of these distributions the asymptotic behaviour of the probabilities of the two polar rules follows the same patterns.     

On the foundations of decision making under partial information

We show how to model incompleteness in the decision maker's judgements, within a Bayesian context, providing axioms which lead us to work with families of values or probabilities and utilities. The proper solution concepts are suggested. On the whole, we provide a more robust decision theory, based on a weaker set of axioms, but embodying coherence, since it essentially implies carrying out a family of coherent decision analyses.     

Treatment with human chorionic gonadotropin for PADAM: A preliminary report

The purpose of this study was to evaluate the efficacy and safety of human chorionic gonadotropin (hCG) for patients with partial androgen deficiency of the aging male (PADAM). Twenty-one patients over 50 years of age with PADAM symptoms were included in this study. Laboratory and endocrinologic profiles were reviewed as appropriate, and PADAM symptoms were judged by means of several questionnaires such as the Aging Males' Symptoms (AMS) scale, short version of the International Index of Erectile Function (IIEF-5), and the Self-rating Depression Scale (SDS). Laboratory and endocrinologic values and symptom scores were evaluated and compared before and after treatment by hCG injection. The treatment period was 8.0 ± 5.0 months (3.0 – 24.0 months). Serum concentrations of testosterone, including total testosterone, calculated free testosterone, and calculated bioavailable testosterone, increased significantly. AMS total scores and subscores decreased significantly after treatment. However, IIEF-5 and SDS scores did not improve. With respect to adverse effects, laboratory tests showed that only red blood cell count, hematocrit and hemoglobin level increased significantly after treatment, however, these values remained within the normal range. No adverse effect was identified after treatment. We conclude that hCG injection may be considered as a treatment for PADAM.     

On Testing the Mean Equivalence of Treatments from Correlated Normal Populations

Let there be k equally correlated treatment populations under consideration, a Studentized range test is proposed to test the hypothesis of average mean equivalence against the alternative hypothesis of inequivalence. The maximum level and minimum power at some least favorable configurations of means are used to calculate the critical value and the required sample size simultaneously when testing a null against an alternative hypothesis. The range test is applied to a real world problem to find out if the stress levels among children at four time periods due to a newly built nearby airport are equivalent.