人口红利的经济社会代价与可持续发展

本文分析了人口红利背后的经济社会代价,意在提请人们注意,人口红利是一把双刃剑,在看到人口红利好处的同时,也要洞察其背后的隐患,不能盲目乐观。我们的真正目的不是要事受人口红利,而是要摆脱对它的依赖。只有利用好人口红利期,在人口机会窗关闭前积极求变,才能实现可持续发展。     

农户个体决策与农民经济组织的内生性——超边际视角下的农民经济组织

单个农户在分工协作中能够获得"1 1>2"的分工经济,通过特定的经济组织来安排单个农户的分工协作就会实现这种分工经济。但是,组织中的单个农户与其他经济主体必然存在着交易费用。当交易费用超过了分工协作的经济性,单个农户就不会选择加入经济组织。地方政府往往不能充分理解单个农户对经济组织中交易费用和相对价格的考虑,这导致了大多数农户不愿选择加入"模式"型的经济组织。因此,地方政府要以自身的分工特征合理融入农民经济组织发展的各个阶段。     

产品质量内部性问题的政府管制

文章引入了对产品质量的分析,将产品质量和数量作为并列的因素进行考察,着重分析了产品质量的内部性问题,并进一步提出了单纯的较大的交易成本和单纯的不对称信息,都不能解释产品质量内部性问题产生的根源,与信息不对称紧密联系的较大的交易成本才是其根源。如何降低这种交易成本就成为政府对产品质量内部性进行管制,提高消费者福利水平的管制重点。     

基于在线算法的改进指数梯度投资组合策略

弱集成算法是对专家意见进行动态加权平均的在线学习算法。近年来,机器学习和人工智能等方法被用来研究在线投资组合问题。该文从弱集成算法的在线学习及其序列决策性角度出发,设计改进的指数梯度在线投资组合策略,以弥补指数梯度在线投资组合策略不能结合交易费用进行分析的缺陷。首先根据指数梯度在线投资组合策略的更新方法构建代表投资策略的专家意见池,并以此为基础应用弱集成算法加权集成专家意见得到改进的指数梯度在线投资组合策略,证明了该策略可与最优专家策略(基准策略)相媲美。其次将交易费用引入到改进的指数梯度在线投资组合策略中,进一步给出对应的投资策略,重要的是理论上证明了该策略实现的平均累积收益与最优专家策略实现的平均累积收益之间的差值存在渐进式下界,从而提高了指数梯度在线投资组合策略的实用性。最后利用国内外股票市场的历史数据进行实证分析,说明了改进的指数梯度在线投资组合策略的可行性和有效性。     

The impact on taxpayer costs of a jail diversion program for people with serious mental illness

Mental illness is prevalent among those incarcerated. Jail diversion is one means by which people with mental illness are treated in the community – often with some criminal justice system oversight – instead of being incarcerated. Jail diversion may lead to immediate reductions in taxpayer costs because the person is no longer significantly engaged with the criminal justice system. It may also lead to longer term reductions in costs because effective treatment may ameliorate symptoms, reduce the number of future offenses, and thus subsequent arrests and incarceration. This study estimates the impact on taxpayer costs of a model jail diversion program for people with serious mental illness. Administrative data on criminal justice and treatment events were combined with primary and secondary data on the costs of each event. Propensity score methods and a quasi-experimental design were used to compare treatment and criminal justice costs for a group of people who were diverted to a group of people who were not diverted. Diversion was associated with approximately $2800 lower taxpayer costs per person 2 years after the point of diversion (p < .05). Reductions in criminal justice costs drove this result. Jail diversion for people with mental illness may thus be justified fiscally.     

苏轼“平淡自然”论及其艺术审美理想

20世纪以来，关于苏轼平淡自然艺术理论研究的文章数量众多，但基本是围绕着苏轼晚年趋于平淡自然风格的追求与他大量的“和陶诗”来谈的。实际上苏轼的“平淡自然”艺术思想有着独特而丰富的内涵，这里从时代风尚、艺术创作、人格境界、情感守护以及人生艺术化等几个方面论述苏轼的“平淡自然”的艺术思想。     

公共治理中的意识形态供给：一种交易费用分析

公共治理的目的是运用公共权力去引导、规范和控制公众的各种活动，运用公共权威维持政治秩序，实现公共资源配置的最优化与社会福利的最大化，最大限度地增进公共利益。由于公众的经济人理性不完全性，政府不得不投入大量资源和公众博弈，以维持保卫公共系统的存续。意识形态通过其无微不至的“观照”面孔和修辞技艺来形塑和开拓政治格局，说服人们相信社会生活就应该如此，诱发人们对政治系统的信任与偏好。意识形态的供给具有降低交易费用，促进政府和社会公众合作与协调发展的功用。     

论新闻计算句子长短的句子标准

新闻语体的句子应该比其他语体的句子短，这是由新闻的易读性决定的。但是目前的一些新闻语言研究中，统计出的句子比其他语体的句子还要长几倍。一些新闻语言研究中同时以单句和复句为单位。单句和复句在语法结构上不是同一层级的语言单位，同时作为计算单位，是违反逻辑的。语法系统中，小句是基本的句子，是传递信息的基本单位。新闻语言研究中也应以小句为计算单位。     

Projectors and linear estimation in general linear models

The paper gives a self-contained account of minimum disper­sion linear unbiased estimation of the expectation vector in a linear model with the dispersion matrix belonging to some, rather arbitrary, set of nonnegative definite matrices. The approach to linear estimation in general linear models recommended here is a direct generalization of some ideas and results presented by Rao (1973, 19 74) for the case of a general Gauss-Markov model

A new insight into the nature of some estimation problems originaly arising in the context of a general Gauss-Markov model as well as the correspondence of results known in the literature to those obtained in the present paper for general linear models are also given. As preliminary results the theory of projectors defined by Rao (1973) is extended.     

Reliability of global sensitivity indices

Uncertainty and sensitivity analysis is an essential ingredient of model development and applications. For many uncertainty and sensitivity analysis techniques, sensitivity indices are calculated based on a relatively large sample to measure the importance of parameters in their contributions to uncertainties in model outputs. To statistically compare their importance, it is necessary that uncertainty and sensitivity analysis techniques provide standard errors of estimated sensitivity indices. In this paper, a delta method is used to analytically approximate standard errors of estimated sensitivity indices for a popular sensitivity analysis method, the Fourier amplitude sensitivity test (FAST). Standard errors estimated based on the delta method were compared with those estimated based on 20 sample replicates. We found that the delta method can provide a good approximation for the standard errors of both first-order and higher-order sensitivity indices. Finally, based on the standard error approximation, we also proposed a method to determine a minimum sample size to achieve the desired estimation precision for a specified sensitivity index. The standard error estimation method presented in this paper can make the FAST analysis computationally much more efficient for complex models.