Estimating Abundance from Presence–Absence Maps via a Paired Negative‐Binomial Model

The estimation of abundance from presence–absence data is an intriguing problem in applied statistics. The classical Poisson model makes strong independence and homogeneity assumptions and in practice generally underestimates the true abundance. A controversial ad hoc method based on negative‐binomial counts (Am. Nat.) has been empirically successful but lacks theoretical justification. We first present an alternative estimator of abundance based on a paired negative binomial model that is consistent and asymptotically normally distributed. A quadruple negative binomial extension is also developed, which yields the previous ad hoc approach and resolves the controversy in the literature. We examine the performance of the estimators in a simulation study and estimate the abundance of 44 tree species in a permanent forest plot.     

A Necessary Condition for the Strong Oracle Property

A problem of using a non‐convex penalty for sparse regression is that there are multiple local minima of the penalized sum of squared residuals, and it is not known which one is a good estimator. The aim of this paper is to give a guide to design a non‐convex penalty that has the strong oracle property. Here, the strong oracle property means that the oracle estimator is the unique local minimum of the objective function. We summarize three definitions of the oracle property – the global, weak and strong oracle properties. Then, we give sufficient conditions for the weak oracle property, which means that the oracle estimator becomes a local minimum. We give an example of non‐convex penalties that possess the weak oracle property but not the strong oracle property. Finally, we give a necessary condition for the strong oracle property.     

Combining Inverse Probability Weighting and Multiple Imputation to Improve Robustness of Estimation

Inverse probability weighting (IPW) and multiple imputation are two widely adopted approaches dealing with missing data. The former models the selection probability, and the latter models data distribution. Consistent estimation requires correct specification of corresponding models. Although the augmented IPW method provides an extra layer of protection on consistency, it is usually not sufficient in practice as the true data‐generating process is unknown. This paper proposes a method combining the two approaches in the same spirit of calibration in sampling survey literature. Multiple models for both the selection probability and data distribution can be simultaneously accounted for, and the resulting estimator is consistent if any model is correctly specified. The proposed method is within the framework of estimating equations and is general enough to cover regression analysis with missing outcomes and/or missing covariates. Results on both theoretical and numerical investigation are provided.     

历史地理学研究中GIS的认知过程及其人类因素考量

GIS技术在历史地理学研究领域的引入,为21世纪历史地理学沉淀积累和蓄势待发提供了新的研究视角和路径。随着GIS技术的普遍运用,尤其是在历史自然地理领域的使用,遂成为该研究方向创新和发展的重要因素。不过,GIS技术在人文地理研究领域中的运用情况则略显滞后,其实质在于受人类因素影响下历史文献数据化的标准问题。此外,GIS技术自身定位不再局限于一种研究手段,而是呈现出向新方法和理论高度的认知过程。     

基于不同法人治理结构的烤烟专业合作社绩效评价

利用陕西省安康、商洛和宝鸡3市38家烤烟专业合作社的调查数据,基于不同法人治理结构视角,运用层次分析法构建绩效评价指标体系对两种不同类型的烤烟专业合作社进行实证分析。研究结果表明:38家烤烟专业合作社可以根据法人治理结构的不同分为“外部委托代理人型”与“内部委托代理人型”两种类型。“外部委托代理人型”烤烟专业合作社在社员人数、理事会核心成员构成比例、股权集中程度及监督力度等法人治理结构方面具有明显的优势,在吸纳了更多的农户入社、提高烤烟专业合作社经济收益的同时,也保证了绝大多数农户在股权分配、民主决策参与及合作社监督等方面的权利。这有利于基层民主的完善,有利于显著提高烤烟专业合作社管理效率,从而提高农户整体烟叶生产水平。因此,改善法人治理结构是促进农民专业合作社发展的重要途径。     

我国金融控股公司立法必要性探析

金融控股公司作为我国金融“分业”体制下实现“混业经营”目的的一种组织创新模式,在我国的发展日益迅速,而我国立法空缺的现状却严重阻碍了其健康发展,也造成了极大的金融风险。文章利用历史分析、比较分析和法经济学的方法,通过对我国金融业历史发展演进的纵向考察,对世界金融控股公司普遍立法现状的横向比较以及金融控股公司作为一种经济组织形式与我国金融立法关系的分析,论证了我国金融控股公司立法的必要性。     

和谐社会与我国行政诉讼制度的发展

行政诉讼是政府和公众之间"利益沟通"的最为权威、正式的法律机制.现阶段,我国的行政诉讼呈现出起诉和受理难、应诉难、审理难、诉讼成本高、当事人胜诉难、执行难等困境,只有通过系统的制度改造,行政诉讼才能真正成为构筑和谐社会的司法公器.     

西部城市公用事业运营模式改革的路径选择——以西部三省(陕西、甘肃、四川)为例

一、引言 城市公用事业是城市为市民提供基础设施和公共服务的重要内容,包括城市供水、供电、供热、供气、公共交通、排水、污水处理、道路桥梁、市政设施、市容卫生、垃圾处理和城市绿化等方面.城市公用事业是城市经济社会发展的载体,直接关系到社会的公共利益和可持续发展.     

城市滨水旧住区问题分析及对策研究——以上海市长风新村街道沿河旧住区为例

一、引言 进入21世纪以来,城市滨水地区由于其悠久的发展历史、丰厚的文化底蕴和重要的城市区位,成为政府、公众和开发商关注的焦点,因此,滨水地带的复兴成为中国城市发展的中心议题之一.     

清代广州十三行在中西交流中的历史地位

清代广州十三行是政府特许的外贸垄断组织。在广州一口通商时期,十三行成为中国走向世界的桥梁,世界透视中国的主要窗口,在中西交流中起着十分重要的作用。