A Class of Efficient Non-parametric K-sample Tests for Multivariate Counting Processes with Frailties

A K -sample testing problem is studied for multivariate counting processes with time-dependent frailty. Asymptotic distributions and efficiency of a class of non-parametric test statistics are established for certain local alternatives. The concept of efficiency is to show that for every non-parametric test in this class, there is a parametric submodel for which the optimal test has the same asymptotic power as the non-parametric one. The theory is applied to analyse a diabetic retinopathy study data set. A simulation study is also presented to illustrate the theory     

Efficient Estimation of a Distribution Function under Quadrant Dependence

LetX₁,X₂, ..., be real-valued random variables forming a strictly stationary sequence, and satisfying the basic requirement of being either pairwise positively quadrant dependent or pairwise negatively quadrant dependent. LetF^ be the marginal distribution function of theX_ips, which is estimated by the empirical distribution functionF_n and also by a smooth kernel-type estimateF_n, by means of the segmentX₁, ...,X_n. These estimates are compared on the basis of their mean squared errors (MSE). The main results of this paper are the following. Under certain regularity conditions, the optimal bandwidth (in the MSE sense) is determined, and is found to be the same as that in the independent identically distributed case. It is also shown thatn MSE(F_n(t)) andnMSE (F^_n(t)) tend to the same constant, asn→∞ so that one can not discriminate be tween the two estimates on the basis of the MSE. Next, ifi(n) = min {k∈{1, 2, ...}; MSE (F_k(t)) ≤ MSE (F_n(t))}, then it is proved thati(n)/n tends to 1, asn→∞. Thus, once again, one can not choose one estimate over the other in terms of their asymptotic relative efficiency. If, however, the squared bias ofF^_n(t) tends to 0 sufficiently fast, or equivalently, the bandwidthh_n satisfies the requirement thatnh³_n→ 0, asn→∞, it is shown that, for a suitable choice of the kernel, (i(n) ?n)/(nh_n) tends to a positive number, asn→∞ It follows that the deficiency ofF_n(t) with respect toF^_n(t),i(n) ?n, is substantial, and, actually, tends to ∞, asn→∞. In terms of deficiency, the smooth estimateF^_n(t) is preferable to the empirical distribution functionF_n(t)     

The calibration of P-values,posterior Bayes factors and the AIC from the posterior distribution of the likelihood

The posterior distribution of the likelihood is used to interpret the evidential meaning of P-values, posterior Bayes factors and Akaike's information criterion when comparing point null hypotheses with composite alternatives. Asymptotic arguments lead to simple re-calibrations of these criteria in terms of posterior tail probabilities of the likelihood ratio. (Prior) Bayes factors cannot be calibrated in this way as they are model-specific.     

Financial management: Development of scales

This study is a contribution to the development of family resource management scales, specifically financial management scales. Principal axis factor analysis, with varimax rotation, is used to assess underlying relationships in 23 family resource management variables related to time and money resources. Reliability and content, construct, and criterion-related validity of the scales are assessed. Two scales that are reliable and have some degree of validity are developed: frequency of financial problems and frequency of financial management. The scales could be used in future research, teaching, or counseling to organize financial management concepts.Preparation of this research was supported in part by the Illinois Agricultural Experiment Station. Data were collected in conjunction with the cooperative regional research project NC-182, Family Resource Utilization as a Factor in Determining Economic Well-Being of Rural Families. Cooperating states are Arizona, California, Illinois, Indiana, Iowa, Kansas, Michigan, and Minnesota.She received her Ph.D. from the University of Illinois; her current research interests include gender roles, family financial management, and economic well-being.Her current research interests include family financial management and consumer bankruptcy. She received her Ph.D. from the University of Missouri.Her current research interests include the economic well-being of various family forms. She received her Ph.D. from the University of Illinois.She received her Ph.D. from the University of Illinois. Her research interests are economic well-being and quality of life.     

中国股市收益率分布函数研究

本文在考察了文献中描述股票收益率的各类分布函数的基础上,以稳定Paretian分布与t分布为备择,研究了沪、深股市各类综指收益率的分布函数的形式,并对分布函数的参数进行了估计。     

On the Effect of Probability Distributions of Input Variables in Public Health Risk Assessment

A central part of probabilistic public health risk assessment is the selection of probability distributions for the uncertain input variables. In this paper, we apply the first-order reliability method (FORM)^(1–3) as a probabilistic tool to assess the effect of probability distributions of the input random variables on the probability that risk exceeds a threshold level (termed the probability of failure) and on the relevant probabilistic sensitivities. The analysis was applied to a case study given by Thompson et al. ⁽⁴⁾ on cancer risk caused by the ingestion of benzene contaminated soil. Normal, lognormal, and uniform distributions were used in the analysis. The results show that the selection of a probability distribution function for the uncertain variables in this case study had a moderate impact on the probability that values would fall above a given threshold risk when the threshold risk is at the 50th percentile of the original distribution given by Thompson et al. ⁽⁴⁾ The impact was much greater when the threshold risk level was at the 95th percentile. The impact on uncertainty sensitivity, however, showed a reversed trend, where the impact was more appreciable for the 50th percentile of the original distribution of risk given by Thompson et al. ⁴ than for the 95th percentile. Nevertheless, the choice of distribution shape did not alter the order of probabilistic sensitivity of the basic uncertain variables.     

Estimation from Zero-Failure Data

When performing quantitative (or probabilistic) risk assessments, it is often the case that data for many of the potential events in question are sparse or nonexistent. Some of these events may be well-represented by the binomial probability distribution. In this paper, a model for predicting the binomial failure probability, P , from data that include no failures is examined. A review of the literature indicates that the use of this model is currently limited to risk analysis of energetic initiation in the explosives testing field. The basis for the model is discussed, and the behavior of the model relative to other models developed for the same purpose is investigated. It is found that the qualitative behavior of the model is very similar to that of the other models, and for larger values of n (the number of trials), the predicted P values varied by a factor of about eight among the five models examined. Analysis revealed that the estimator is nearly identical to the median of a Bayesian posterior distribution, derived using a uniform prior. An explanation of the application of the estimator in explosives testing is provided, and comments are offered regarding the use of the estimator versus other possible techniques.     

中国股市收益率分布特征研究

应用修正Weibull分布对上海综合指数收益率和深圳成分指数收益率的分布状况进行研究。结果表明:经过简单的移位变换后,上证综指收益率和深成指收益率可完全用修正Weibull分布来刻画;大收益率服从次指数分布,小收益率服从超指数分布;两股指收益率的概率分布存在一些差异,上证综指的波动性大于深成指的波动性;沪深股市收益率的分布在1996年以后发生了较大的变化,其中沪市变化更大。     

不同规模农地抵押贷款可得性研究

以南阳市427户农户调查数据为样本,运用二元Logit回归模型对三类不同土地规模农户的农地抵押贷款可得性及其影响因素进行分析。结果发现,户主年龄、文化程度、家庭收入、房屋价值、社会资本、对贷款政策了解度及土地规模差异均对农户农地抵押贷款可得性具有显著影响。其中,家庭收入与房屋价值是影响不同土地规模农户农地抵押贷款可得性的共同因素,土地规模是影响农地抵押贷款可得性最为直接的关键性因素,随着土地规模增加,金融机构贷款审批更注重农户个人信用程度、社会资本和风险保障措施。     

异种自由刑数罪并罚规则研究

异种自由刑数罪并罚是在原有数罪并罚规则基础之上,针对多样化的犯罪现象与司法适用而设置的规则。根据我国现行《刑法》规定的异种自由刑并罚内容,吸收原则与并科原则各自蕴含着合理性依据。然而立足于整体数罪并罚的规则,此种规定却存在二者相互矛盾以及刑罚轻重的冲突,给理论研究与实践适用带来困扰。基于此,通过对域外异种自由刑数罪并罚规则的考察,借鉴其中折抵和限制加重原则的内容,提出我国异种自由刑并罚规则的改进建议:对有期徒刑和拘役刑的并罚采用综合折抵原则与限制加重原则的方式,而对有期徒刑、拘役刑和管制刑的并罚继续采用并科原则,从而更好地实现数罪并罚的适用。