高风险、高成本背景下棉农种植决策分析

依据对新疆自治区及新疆生产建设兵团341户棉农调查,通过分别构建Logit二元选择模型,分析在高市场风险、高生产成本等复杂背景下,棉农种植决策差异。研究结果表明,户主年龄、种植面积、亩均成本、棉花单产、种植经验、对成本预期6项指标对兵团及自治区棉农种植决策均有着显著影响。不同的是棉花收入占家庭总收入比重仅在自治区模型中通过显著性检验,而是否机采也仅在兵团模型中通过了显著性检验。文章基于此实证结果并结合相关理论分析,提出促进棉农积极植棉,增收的相关建议。     

The linked survival prospects of siblings: Evidence for the Indian states

This paper reports an analysis of micro-data for India that shows a high correlation in infant mortality among siblings. In 13 of 15 states, we identify a causal effect of infant death on the risk of infant death of the subsequent sibling (a scarring effect), after controlling for mother-level heterogeneity. The scarring effects are large, the only other covariate with a similarly large effect being mother's (secondary or higher) education. The two states in which evidence of scarring is weak are Punjab, the richest, and Kerala, the socially most progressive. The size of the scarring effect depends upon the sex of the previous child in three states, in a direction consistent with son-preference. Evidence of scarring implies that policies targeted at reducing infant mortality will have social multiplier effects by helping avoid the death of subsequent siblings. Comparison of other covariate effects across the states offers some interesting new insights.     

A restricted Liu estimator for binary regression models and its application to an applied demand system

In this article, we propose a restricted Liu regression estimator (RLRE) for estimating the parameter vector, β, in the presence of multicollinearity, when the dependent variable is binary and it is suspected that β may belong to a linear subspace defined by Rβ?=?r. First, we investigate the mean squared error (MSE) properties of the new estimator and compare them with those of the restricted maximum likelihood estimator (RMLE). Then we suggest some estimators of the shrinkage parameter, and a simulation study is conducted to compare the performance of the different estimators. Finally, we show the benefit of using RLRE instead of RMLE when estimating how changes in price affect consumer demand for a specific product.     

Maximum-likelihood estimation of the random-clumped multinomial model as a prototype problem for large-scale statistical computing

Numerical methods are needed to obtain maximum-likelihood estimates (MLEs) in many problems. Computation time can be an issue for some likelihoods even with modern computing power. We consider one such problem where the assumed model is a random-clumped multinomial distribution. We compute MLEs for this model in parallel using the Toolkit for Advanced Optimization software library. The computations are performed on a distributed-memory cluster with low latency interconnect. We demonstrate that for larger problems, scaling the number of processes improves wall clock time significantly. An illustrative example shows how parallel MLE computation can be useful in a large data analysis. Our experience with a direct numerical approach indicates that more substantial gains may be obtained by making use of the specific structure of the random-clumped model.     

农民工家庭迁移状态的演进及其影响因素研究——基于山东省951户的调查数据

根据山东省951户农民工家庭的调查数据,利用多元Logit模型和扩展的Oaxaca-Blinder分解方法,系统分析了农民工家庭向城镇迁移过程中迁移状态的演进及其影响因素。研究表明,初次离乡和定居城市两种演进形式的实现难度较小,而举家迁移和直接定居城市两种演进形式的实现难度较大;农民工家庭劳动力的城镇务工状况及其农村经济状况是影响农民工家庭迁移状态演进的决定性因素。     

Chi–square tests for comparing vectors of proportions for several cluster samples

Test statistics are developed for comparing vectors of proportions obtained from several independent two–stage cluster samples. It is assumed that clusters are selected with probability proportional to size for each sample. Wald's general method of constructing quadratic forms is used to obtain a large sample chi–square test. More easily evaluted chi–square tests are derived from the Dirichlet–multinnomial model. Corresponding goodness–of–fit test for the Dirichlet–multinomial model are also derived.     

Use,of andrews' function plot technique to construct control curves for multivariate process

This paper describes a method for quality control of product when it depends on several characteristics. The proposed procedure is graphical in nature and is based on Andrews' function plot technique. The method is illust¬rated with the help of a small simulated data.     

The negative multinomial logit model

A polychotomous logit model is defined for negative multinomial frequency counts within independent populations. An efficient estimator of the model parameters and estimator covariance matrix is given in closed form. Minimum chi-square and Wald tests are presented.     

A transformation for estimating the trinomial logit model with grouped data

For logit models where the outcome variables are the proportions of individuals falling into each of three categories, this paper develops a data transformation through which GLS estimates can be obtained by running OLS on the transformed data.     

Some remarks on the chi-squared test with both margins fixed

Under the hypothesis of independence, the chi-squared test statistic for independence in a two-way contingency table follows an asymptotic chi-squared distribution under both a multinomial and a product-multinomial models. Alalouf(1987) showed the same result holds for the third case where both margins are fixed. In this paper an intuitively easier way of proof using the conditional limit theorems is suggested and some points are discussed.