农户农用化学品减施意愿及影响因素研究——基于山东省H镇208份菜农问卷调查的实证

减少农用化学品投入对减轻农业生态环境污染、保障农产品质量安全和促进农业可持续发展具有重要意义。基于山东省H镇208份菜农的调查问卷数据,依托成本收益和生产要素理论,采用Logistic模型实证分析菜农农用化学品减施意愿及影响因素。结果表明:54.33%的农户愿意减少农用化学品投入;影响因素方面,农户年龄在5%的水平下有显著的负向影响,受教育程度、农药残留认知和化肥过量施用导致重金属污染的认知分别在5%、1%和5%的水平下有显著的正向影响;农用化学品年投入成本和农药每公顷平均花费对农户农用化学品减施意愿的影响并不显著,但模型系数均为正,表明这些变量对农户减少农用化学品投入具有一定程度上的正效应。最后,基于研究结论分别从政府、农资经销商和农户角度提出相关政策建议。     

我国城镇基本养老保险水平影响因素的经验研究

养老保险水平包含覆盖水平和待遇水平两个方面,本文运用国家统计局全国抽样调查数据,通过logistic模型和Tobit模型分别对影响城镇基本养老保险覆盖水平和待遇水平的因素进行了实证分析,重点研究制度性因素对养老保险水平的影响。得出如下结论:第一,我国城镇基本养老保险水平同时受制度性因素和个人特征因素影响,并且制度性因素对养老保险覆盖水平的作用突出。第二,在正规部门、第二产业就业以及具有固定或长期劳动合同的劳动者更有可能加入养老保险体系,其待遇水平与工作单位的规范性及所在行业也具有显著关系。第三,所处地区、家庭储蓄水平、文化程度、是否为党员及更换过工作单位等个人特征因素对养老保险水平也具有显著影响。     

Dynamics of Internal Migration Determinants for American Jews, 1985–1990 and 1995–2000

This paper examines how individual characteristics and structural factors have changed in determining Jewish internal migration in the U.S. between 1985–1990 and 1995–2000. Multinomial logistic regression analysis of the 1990 and 2000 National Jewish Population Surveys shows that socio-demographic characteristics have both increased their power to explain variation in 5-year migration and have become more similar for intra- and interstate migration. Further analysis added migration status at the beginning-of-period, state context of residence characteristics, and ethnic concentration to the explanatory variables. Results from logistic regression analysis, which was limited to interstate mobility, were very much in accordance with the observations of the single-level analysis of the socio-demographic variables. Additional findings suggest that previous mobility increases subsequent interstate migration; that per capita income does not have a meaningful effect on migration; that unemployment encourages migration (yet later this relationship turned negative); and that warm climate deters migration. The importance of ethnic concentration has weakened over time albeit maintained statistically significant. Finally, when the two surveys were integrated into one data set, “time” enhances the tendency of Jews to migrate. The results are discussed in the context of ethnic diversity in contemporary America.

Immigration,ethnicity, and housing—Success hierarchies in Israel

The study assesses housing hierarchies among immigrants in Israel by investigating three different but complementary paths: homeownership, crowding, and access to housing goods. Data from the most recent Israeli census in 1995 (the 20% version file) allows us to classify the immigrant population by 46 countries or areas of origin, each meeting the criterion of having a minimum of 100 sample cases. I controlled for several confounding factors: immigration characteristics, community of residence, demographic and human-capital variables, household composition, and housing characteristics. The results of multivariate analyses suggest that membership in approximately half of the immigrant groups has a statistically significant effect on homeownership. Representing very different origin groups from developing countries in Asia and Africa, as well as developed areas in Western Europe and America, most of the effects are negative relative to the reference group of Polish Jews. The pace of home acquisition is fastest among immigrants from several former Soviet republics and slowest among Syrian and Ethiopian Israelis. A better ethnic hierarchy was found for the other two characteristics, crowding and housing goods, with immigrants from Asia, Africa, and Eastern Europe being at a disadvantage. Many of these gaps close as immigrants purchase housing and gain tenure in Israel. The pace of advancement, however, is not uniform. I speculate that the differences in pace reflect structural characteristics, cultural background, and immigration processes, as well as absorption policy, which were not fully indexed by the census data. The discussion addresses broader implications of the findings for ethnic differences and social stratification in immigration countries.     

Confidence estimation via the parametric bootstrap in logistic joinpoint regression

We consider asymptotic properties of the maximum likelihood and related estimators in a clustered logistic joinpoint model with an unknown joinpoint. Sufficient conditions are given for the consistency of confidence bounds produced by the parametric bootstrap; one of the conditions required is that the true location of the joinpoint is not at one of the observation times. A simulation study is presented to illustrate the lack of consistency of the bootstrap confidence bounds when the joinpoint is an observation time. A removal algorithm is presented which corrects this problem, but at the price of an increased mean square error. Finally, the methods are applied to data on yearly cancer mortality in the US for individuals age 65 and over.     

Some new methods to solve multicollinearity in logistic regression

The binary logistic regression is a widely used statistical method when the dependent variable is binary or dichotomous. In some of the situations of logistic regression, independent variables are collinear which leads to the problem of multicollinearity. It is known that multicollinearity affects the variance of maximum likelihood estimator (MLE) negatively. Thus, this article introduces new methods to estimate the shrinkage parameters of Liu-type logistic estimator proposed by Inan and Erdogan (2013 Inan, D., Erdogan, B. E. (2013). Liu-type logistic estimator. Communications in Statistics-Simulation and Computation 42(7):1578–1586. [Google Scholar]) which is a generalization of the Liu-type estimator defined by Liu (2003 Liu, K. (2003). Using Liu-type estimator to combat collinearity. Communications in Statistics: Theory and Methods 32(5):1009–1020. [Google Scholar]) for the linear model. A Monte Carlo study is used to show the effectiveness of the proposed methods over MLE using the mean squared error (MSE) and mean absolute error (MAE) criteria. A real data application is illustrated to show the benefits of new methods. According to the results of the simulation and application proposed methods have better performance than MLE.     

A skew logistic distribution as an alternative to the model of van Staden and King

The logistic distribution is a simple distribution possessing many useful properties and has been used extensively for analyzing growth. Recently, van Staden and King proposed a quantile-based skew logistic distribution. In this paper, we introduce an alternative skew logistic distribution. We then establish recurrence relations for the computation of the single and product moments of order statistics from the standard skew logistic distribution by using the moments of order statistics from the standard half logistic distribution. These enable an efficient computation of means, variances and covariances of order statistics from the skew logistic distibution for all sample sizes. The results become useful in determining the best linear unbiased estimators of the location and scale paramters of the skew logistic distribution. Finally, we provide an example to illustrate the usefulness of the developed model and then compare its fit with that provided by the model of van Staden and King.     

沿江开发下的水质、水量的优化配置

本文根据沿江流域水(资源)环境状况,首先建立经济增长与水环境污染模型,运用单变量时序方法,研究污染指标等单变量数据与该地区的经济增长的内在相关度;其次,在分析江苏经济增长方式的条件下,建立新一轮增长周期下江苏总用水量Logistic预测模型,预测江苏用水趋势和走向;最后预测全省以及沿江八市的将来水资源所面临的问题,并提出合理的沿江开发水资源优化配置方案。     

Bayesian estimation methods for contingency tables

Summary A method of inputting prior opinion in contingency tables is described. The method can be used to incorporate beliefs of independence or symmetry but extensions are straightforward. Logistic normal distributions that express such beliefs are used as priors of the cell probabilities and posterior estimates are derived. Empirical Bayes methods are also discussed and approximate posterior variances are provided. The methods are illustrated by a numerical example.     

妇女文化精神生活满意感影响因素分析

本文利用全国妇联、国家统计局2000年12月第二期妇女地位调查的数据资料,对我国妇女的文化精神生活状况做了大体描述,并利用Logistic回归对妇女文化精神满意感的影响因素进行了分析。研究发现,妇女年龄、民族、受教育年限、物质生活满意感、工作能力发挥满意感、文体活动的参与、家庭婚姻生活满意感等因素对妇女文化精神生活的满意感起着重要的影响作用,最后对提高妇女文化精神生活提出了相关建议。