Survival on the Titanic: Illustrating Wald and Lagrange Multiplier Tests for Proportions and Logits

Abstract: Students are interested in lecture examples and class exercises involving data connected to the maiden voyage and the sinking of the liner Titanic. Information on the passengers and their fate can be used to explore relationships between various tests for differences in survival rates between different groups of passengers. Among the concepts the authors examined are tests for differences of proportions using a normal distribution, a chi-square test for independence, a test for the equality of two logits, and a test for the significance of the coefficient of a binary variable in logit model. The authors examined the relationship between Wald and Lagrange Multiplier test statistics and give two related examples.     

论四川林业碳汇贸易的发展潜力

近年来四川提出建设西部综合交通枢纽,建设西部物流中心、商贸中心和金融中心,以及建设重要战略资源开发基地、现代加工制造业基地、科技创新产业化基地、农产品深加工基地的发展思路,为整合林业大省资源,发展林业碳汇贸易带来良好机遇。文章考查了四川林业碳汇贸易发展的内外因素,重点分析了林业碳汇贸易的发展潜力,提出了立足四川省情,结合国际国内市场的顺势发展路径。     

农户禀赋对农户融入农产品供应链意愿及方式的影响基于西南地区的农户调查

目的 通过对微观农户调查数据的分析,探究人力资本禀赋、社会资本禀赋、经济资本禀赋和自然资本禀赋对农户融入农产品供应链意愿及方式的影响。方法 文章运用二元Logit模型分析农户禀赋各变量对农户融入农产品供应链意愿的影响,运用多项Logit模型分析农户禀赋各变量对“农户+合作社”“农户+公司”和“农户+合作社+公司”3种融入方式影响。结果 缺乏经营经验、农业收入高、不能筹资、耕地面积小的农户融入农产品供应链的意愿较低。户主受教育程度高、学习能力强、耕地面积大的农户更倾向以“农户+合作社”方式融入供应链。学习能力差、家庭人口少、家里有村干的农户选择以“农户+公司”方式融入供应链的可能性较大。有经营经验、培训经历、亲戚数量少、家庭收入高、农业收入低、能筹资的农户更倾向以“农户+合作社+公司”方式融入供应链。交通便利及靠近乡村旅游地区的农户对所有融入农产品供应链的方式均不感兴趣。结论 要破除农户融入农产品供应链的禀赋障碍,科学引导农户以合适的方式融入农产品供应链,重视条件适宜地区农户进行农产品直销的优势和意愿。     

KDN型定氮仪测定粮食中粗蛋白质含量的相关问题探讨

目前测定蛋白质的方法和仪器很多,为了提高蛋白质含量检测结果的准确性和检测效率,依据GB/T 5511-2008《谷物和豆类氮含量测定和粗蛋白质含量计算凯氏法》要求,常用定氮仪来测定粮食中粗蛋白质含量。对此方法中化学试剂硫酸的选择及实际操作进行了探讨。     

Economic design of one-sided screening procedures based on a correlated variable with all parameters unknown

Summary Economic design of one-sided screening procedures for improving outgoing product quality based on a screening variable is considered for the case with all parameters unknown. It is assumed that the performance and screening variables are jointly normally distributed and that costs are incurred by screening inspection, acceptance of an imperfect item, and disposition of a rejected one. A method for finding optimal cutoff value based on the predictive distribution is presented.     

中国服装虚拟企业的供应商区域选择

通过对虚拟企业和产业集群的概念、特征的介绍，提出了中国服装虚拟企业供应商区域选择的原则及方法。并根据提出的基本原则，结合服装行业的实例提出了基于产业集群的供应商区域的选择方法。     

经济结构调整视角下区域产业集群的识别与选择

笔者以当前经济结构调整的要求为视角,确定现代产业集群的选择基准,在此基础上构建产业集群选择的指标体系,然后利用因子分析法,以西安市制造业为例分析各个产业集群的效果,最终筛选出该区域优势产业集群为:以汽车制造和航空航天器制造为主的交通运输设备制造业产业集群;以中药材和化学药品为主的医药制造业产业集群;电器机械及器材制造业产业集群。     

Assessing effects of federal crop insurance supply on acreage and yield of specialty crops

Crop insurance may affect harvested acreage and yield by influencing producers’ behavior such as land allocation and input use. Although specialty crops are a major source of farm income, especially on the U.S. west coast, they have not received as much attention as field crops in previous empirical studies. This paper assesses the effect of moral hazard and adverse selection associated with the federal crop insurance program (FCIP) on the acreage and yield of major specialty crops in California. An econometric method that expands the switching regression model is developed to assess the effect. Results suggest that federal crop insurance can change specialty crop growers’ production responses to climate and soil conditions. The moral hazard effect tends to increase the acreage and yield of the specialty crops, whereas the adverse selection effect tends to have the opposite effect. The overall effect of the FCIP on acreage and yield of specialty crops is found to be moderate.     

Policy lessons from spatiotemporal enrollment patterns of payment for ecosystem service programs in Argentina

Payment for ecosystem services schemes (PES) are lauded as a market-based solution to curtail deforestation and restore degraded ecosystems. However, PES programs often fail to conserve sites under strong long-term deforestation pressures. Underperformance, in part, is likely due to adverse selection. Spatial adverse selection occurs when landowners are more likely to enroll parcels with low deforestation pressure than parcels with high deforestation pressure. Temporal adverse selection arises when parcels are enrolled for short time periods. In both cases, financial resources are allocated without having a sizeable impact on long-term land use change. Improving program performance to overcome these shortcomings requires understanding attributes of landowners and their parcels across large scales to identify spatial and temporal enrollment patterns that drive adverse selection. In this paper, we examine these patterns in Argentina’s PES program in Chaco forest, a global deforestation hotspot. Our study area covers 252,319 km². Results from multinomial logistic regression models showed that large parcels of enrolled land and parcels owned by absentee landowners exhibit greater evidence of spatiotemporal adverse selection than smaller parcels or parcels owned by local landowners. Furthermore, parcels managed under land use plans for conservation and restoration are more likely to be associated with adverse selection than parcels managed for financial returns such as harvest of non-timber forest products, silviculture, and silvopasture. However, prior to recommending that PES programs focus on land uses with higher potential earnings, a greater understanding is needed of the degree to which these land uses meet ecological and biodiversity goals of PES programs. We suggest that increased spatial targeting of enrollment, along with enrollment of local landowners and further incentives for land uses that support conservation and restoration, could promote long-term conservation of forest lands.     

Early Experience and Later Outcomes of Education: Schooling Transition Evidence from Indonesia

This paper investigates the effect of early school experience on later educational attainment. Using the Indonesia Family Life Survey (IFLS), we find that students who repeat a grade at primary school are less likely to progress to junior high school. We also find that grade retention is associated with lower rates of transition from junior high school to senior high school. The relationship persists across years and samples. Meanwhile, the age of students when starting school and the hours they spend there have limited effects on whether they continue their schooling. We also observe that the effects of parental education and household income on the transition of students from primary school to junior high school are weakening. Given the long-term impact of grade retention, policymakers should be cautious when recommending it for underachieving children and should look for alternatives.