重大疫情下的农村封闭式治理：情境、过程与结果——基于桂中H村的调研分析

小农户分为纯小农户、农业兼业户、非农兼业户和非农农户四种类型,乡村振兴视角下探索分化小农户的差异化发展路径尤为重要。混合型发展基于高度分化和异质化的小农户群体特征,分别采用转型之路、多元之路、特色之路和选择之路,统筹推进四类小农户实现分型发展,综合推进小农户嵌入现代农业发展轨道,引导小农户积极融入业态培育和产业培育当中,助力农业农村新旧动能实现平稳转换。     

新型农业经营主体嵌入式培育及其带动作用——以石城为例

发挥新型农业经营主体对小农户的带动作用,是促进小农户与现代农业发展有机衔接的关键。江西石城县着眼于“培养农村致富带头人,打造一支不走的扶贫工作队”,立足县域脱贫与发展需要实施了“千人铸造计划”,该计划发挥县级行政动员优势并扎根乡土社会,从培育方案、产业选择、社会基础、组织设置与政策支持等多方面着手,推动了新型农业经营主体的嵌入式培育及其内生带动作用激发,形成了新型农业经营主体带动小农户发展的实践范例。石城经验体现了我国县域政府独特的行政动员机制及其嵌入乡土社会的本土创新,具有重要的推广价值,可为乡村振兴战略下培育扎根乡土致富带头人及实现小农户与现代农业发展有机衔接提供有益启示。     

Study of partial least squares and ridge regression methods

This article considers both Partial Least Squares (PLS) and Ridge Regression (RR) methods to combat multicollinearity problem. A simulation study has been conducted to compare their performances with respect to Ordinary Least Squares (OLS). With varying degrees of multicollinearity, it is found that both, PLS and RR, estimators produce significant reductions in the Mean Square Error (MSE) and Prediction Mean Square Error (PMSE) over OLS. However, from the simulation study it is evident that the RR performs better when the error variance is large and the PLS estimator achieves its best results when the model includes more variables. However, the advantage of the ridge regression method over PLS is that it can provide the 95% confidence interval for the regression coefficients while PLS cannot.     

An efficient and fast algorithm for estimating the frequencies of superimposed exponential signals in zero-mean multiplicative and additive noise

In this paper, we consider the superimposed exponential signals in zero-mean multiplicative and additive noise when all the noise are independently and identically distributed. We use a three-step iterative procedure to estimate the frequencies of the considered model. It is observed that the estimators are consistent and work quite well in terms of biases and mean square errors. Moreover, the convergence rate of the estimators attains O _p (N ^?3/2), which is the best convergence rate in the case of only additive noise and constant amplitude.     

后改制时代中小型出版社发展模式探析

伴随着出版业转企改制的全面完成,中小型出版单位处在一个变幻莫测的拐点,针对这一现状,阐述了亟需关注与解决的核心问题:中小型出版社如何在竞争中获得持续发展。进而从出版主体的准确定位、出版内容的理性选择等方面分析,得出了用现代企业的发展理念促进中小型出版社均衡发展这一结论。研究结果为中小出版单位发展具有指导作用。     

Threshold Estimation for Stochastic Processes with Small Noise

Consider a process satisfying a stochastic differential equation with unknown drift parameter, and suppose that discrete observations are given. It is known that a simple least squares estimator (LSE) can be consistent but numerically unstable in the sense of large standard deviations under finite samples when the noise process has jumps. We propose a filter to cut large shocks from data and construct the same LSE from data selected by the filter. The proposed estimator can be asymptotically equivalent to the usual LSE, whose asymptotic distribution strongly depends on the noise process. However, in numerical study, it looked asymptotically normal in an example where filter was chosen suitably, and the noise was a Lévy process. We will try to justify this phenomenon mathematically, under certain restricted assumptions.     

Models for the analysis of C-reactive protein in statin trials

Elevation in C-reactive protein (CRP) is an independent risk factor for cardiovascular disease progression and levels are reduced by treatment with statins. However, on-treatment CRP, given baseline CRP and treatment, is not normally distributed and outliers exist even when transformations are applied. Although classical non-parametric tests address some of these issues, they do not enable straightforward inclusion of covariate information. The aims of this study were to produce a model that improved efficiency and accuracy of analysis of CRP data. Estimation of treatment effects and identification of outliers were addressed using controlled trials of rosuvastatin. The robust statistical technique of MM-estimation was used to fit models to data in the presence of outliers and was compared with least-squares estimation. To develop the model, appropriate transformations of the response and baseline variables were selected. The model was used to investigate how on-treatment CRP related to baseline CRP and estimated treatment effects with rosuvastatin. On comparing least-squares and MM-estimation, MM-estimation was superior to least-squares estimation in that parameter estimates were more efficient and outliers were clearly identified. Relative reductions in CRP were higher at higher baseline CRP levels. There was also evidence of a dose-response relationship between CRP reductions from baseline and rosuvastatin. Several large outliers were identified, although there did not appear to be any relationships between the incidence of outliers and treatments. In conclusion, using robust estimation to model CRP data is superior to least-squares estimation and non-parametric tests in terms of efficiency, outlier identification and the ability to include covariate information.     

促进中小企业发展初探——以南宁市为例

随着社会主义市场经济的深入发展和不断完善,我国中小企业将越来越发展壮大,在经济与社会发展中的地位和作用也会越来越重要。南宁市中小企业发展存在人才瓶颈、融资瓶颈、管理瓶颈、信用瓶颈、创新瓶颈、战略瓶颈等问题,因此应抓好制度创新、产品创新、技术创新、环境创新等。     

An empirical investigation of the box-cox model and a nonlinear least squares alternative

In this paper we present a generalized functional form estimator, recently developed by jeffrey Wooldridge; and then we compare it empirically to the popular Box-Cox (BC) estimator using three data sets. We begin by briefly reviewing the drawbacks of the BC estimator. We Then introduce the nonlinear lest squares (NLS) alternative of Wooldridge which retains the desirable qualities of the BC estimator without the associated theoretical problems. We continue by applying both the BC and the NLS models to data from three classic hedonic regression studies and then compare the estimation resuts-point estimates, inferences and fitted values. The estimations include a wage rate equation, and two computer hedonic regression equations, one using data from a classic study by Gregory Chow and the other using an IBM data set that formed the basis of the new official BLS computer price index.     

Optimal design of complex experiments with qualitative factors of influence

A complex experiment with qualirarive factors influencing the outcome of the experiment can be seen as a general ANOVA setup. A design of such an experiment will be the assignment at which of the possible levels of the factors the actual experiment should be performed. In this paper optimal designs of such experiments will be characterized with respect to three different optimality criteria including the so called uniform optimality of a design. The possible applications of the main optimization result providing these characterizations can be used to more general experiments. The particular results on these generalizations will be indicated at the end of this paper.