A STOCHASTIC LOGISTIC MODEL WITH TIME DELAY

The stochastic version of the logistic model for population growth is generalized to take account of continuously distributed time delay with an exponentially decaying kernel. The theory of diffusion processes is used to analyse the probability density function of the population size. The explicit expression for the stationary distribution is worked out and the effect of time delay on various statistics is discussed.     

港口设施建设的多元化筹资方式研究

研究我国港口设施筹资模式对促进我国港口的发展有着重大的现实意义.本文由四个部分组成,从我国港口的现行筹资模式入手进行分析,找出港口设施现行筹资模式的局限性,结合我国港口实际情况对其现行筹资模式进行创新,并在此基础上总结出我国港口设施筹资模式改革的几点启示.     

失地农民城市融入水平及影响因素分析——基于武汉市的调查数据

农民失去土地之后,既有别于传统农民,又不同于城市居民,成为一个边缘群体。失地农民城市融入问题是城市化进程中亟需解决的重要问题。由经济状况、社会互动和心理认同三个一级维度和相应二级指标构成的指标体系衡量失地农民城市融入水平,并以武汉市失地农民为例进行实证分析。二元Logistic回归分析表明年龄、性别、受教育年限、是否愿意在城市生活的心理偏好、土地补偿标准、社会保障政策满意度等个体因素和政策因素共同影响失地农民城市融入水平。从经济、社会、心理多维度,从政府、社会和个体多主体出发,促进失地农民城市融入是今后努力方向。     

利率市场化条件下上市商业银行财务风险评价

选取上市商业银行2011~2013年的14个财务指标,首先运用因子分析法提取主因子,其次将提取的主因子进行聚类分析,改变传统的二分类,将财务风险划分为四类,最后通过寻找各类银行财务风险之间具有显著性差异的指标,并对这些指标提取主因子,采用多分类Logistic回归法构建一个上市商业银行财务风险评测模型,以期能有效地识别风险,实证结果表明,模型预测能力较好。     

New Folded Models for the Log-Transformed Norwegian Fire Claim Data

Folded distributions are useful models in statistics. However, not much is known beyond the folded normal distribution introduced in the 1960s. Here, we introduce several new folded distributions. Statistical properties of each distribution are derived. Applications are provided to the Norwegian fire claim data.     

A simple alternative to the likelihood ratio test in a logistic discrimination problem

We consider the problem of hypothesis-testing under a logistic model with two dichotomous independent variables. In particular, we consider the case in which the coefficients β₁, and β₂ of these variables are known on an a priori basis to not be of opposite sign. For this situation we show that there exists a simple nonparametric altenative to the likelihood ratio test for testing H₀: β₁ = β₂ = 0 VS.H₁ at least one β₁ = 0. We find the asympotic relative efficiency of this test and show that it exceeds 0.90 under a wide range of conditions. We also given an example.     

Nonparametric prediction analysis for binary data

A nonparametric inference algorithm developed by Davis and Geman (1983) is extended problem. The algorithm and applied to a medical prediction employs an estimation procedure for acquiring pairwise statistics among variables of a binary data set, allows for the data-driven creation of interaction terms among the variables, and employs a decision rule which asymptotically gives the minimum expected error. The inference procedure was designed for large data sets but has been extended via the method of cross-validation to encompass smaller data sets.     

Likelihood-based cross-validation score for selecting the smoothing parameter in maximum penalized likelihood estimation

Maximum penalized likelihood estimation is applied in non(semi)-para-metric regression problems, and enables us exploratory identification and diagnostics of nonlinear regression relationships. The smoothing parameter A controls trade-off between the smoothness and the goodness-of-fit of a function. The method of cross-validation is used for selecting A, but the generalized cross-validation, which is based on the squared error criterion, shows bad be¬havior in non-normal distribution and can not often select reasonable A. The purpose of this study is to propose a method which gives more suitable A and to evaluate the performance of it.

A method of simple calculation for the delete-one estimates in the likeli¬hood-based cross-validation (LCV) score is described. A score of similar form to the Akaike information criterion (AIC) is also derived. The proposed scores are compared with the ones of standard procedures by using data sets in liter¬atures. Simulations are performed to compare the patterns of selecting A and overall goodness-of-fit and to evaluate the effects of some factors. The LCV-scores by the simple calculation provide good approximation to the exact one if λ is not extremeiy smaii Furthermore the LCV scores by the simple size it possible to select X adaptively They have the effect, of reducing the bias of estimates and provide better performance in the sense of overall goodness-of fit. These scores are useful especially in the case of small sample size and in the case of binary logistic regression.     

NONNORMAL REGRESSION. I. SKEW DISTRIBUTIONS

In a linear regression model of the type y= θ X+e, it is often assumed that the random error eis normally distributed. In numerous situations, e.g., when ymeasures life times or reaction times, etypically has a skew distribution. We consider two important families of skew distributions, (a) Weibull with support IR: (0, ∞) on the real line, and (b) generalised logistic with support IR: (?∞, ∞). Since the maximum likelihood estimators are intractable in these situations, we derive modified likelihood estimators which have explicit algebraic forms and are, therefore, easy to compute. We show that these estimators are remarkably efficient, and robust. We develop hypothesis testing procedures and give a real life example. Symmetric families of distributions, both long and short tailed, will be considered in a future paper.     

Semiparametric ROC surface estimation for continuous diagnostic tests via polytomous logistic regression procedures

In this paper, we propose a semiparametric method of estimating receiver operating characteristic (ROC) surfaces for continuous diagnostic tests under density ratio models. Implementation of our method is easy since the usual polytomous logistic regression procedures in many statistical software packages can be employed. A simulated example is provided to facilitate the implementation of our method. Simulation results show that the proposed semiparametric ROC surface estimator is more efficient than the nonparametric counterpart and the parametric counterpart whether the normality assumption of data holds or not. Moreover, some simulation results on the underlying semiparametric distribution function estimators are also reported. In addition, some discussions on the proposed method as well as analysis of a real data set are provided.