Assessment of modeling longitudinal binary data based on graphical methods

Longitudinal categorical data are commonly applied in a variety of fields and are frequently analyzed by generalized estimating equation (GEE) method. Prior to making further inference based on the GEE model, the assessment of model fit is crucial. Graphical techniques have long been in widespread use for assessing the model adequacy. We develop alternative graphical approaches utilizing plots of marginal model-checking condition and local mean deviance to assess the GEE model with logit link for longitudinal binary responses. The applications of the proposed procedures are illustrated through two longitudinal binary datasets.     

On tests of symmetry,marginal homogeneity and quasi-symmetry in two-way contingency tables based on minimum φ-divergence estimator with constraints

The restricted minimum φ-divergence estimator, [Pardo, J.A., Pardo, L. and Zografos, K., 2002, Minimum φ-divergence estimators with constraints in multinomial populations. Journal of Statistical Planning and Inference, 104, 221–237], is employed to obtain estimates of the cell frequencies of an I×I contingency table under hypotheses of symmetry, marginal homogeneity or quasi-symmetry. The associated φ-divergence statistics are distributed asymptotically as chi-squared distributions under the null hypothesis. The new estimators and test statistics contain, as particular cases, the classical estimators and test statistics previously presented in the literature for the cited problems. A simulation study is presented, for the symmetry problem, to choose the best function φ₂ for estimation and the best function φ₁ for testing.     

Multivariate normal estimation: the case (n < p)

Estimation in the multivariate context when the number of observations available is less than the number of variables is a classical theoretical problem. In order to ensure estimability, one has to assume certain constraints on the parameters. A method for maximum likelihood estimation under constraints is proposed to solve this problem. Even in the extreme case where only a single multivariate observation is available, this may provide a feasible solution. It simultaneously provides a simple, straightforward methodology to allow for specific structures within and between covariance matrices of several populations. This methodology yields exact maximum likelihood estimates.     

On the construction of optimal experimental designs: a penalty approach

Tn optimal experimental design theory there are well-known situations, in which additional constraints are implied to the design set. These constraints destroy in general the simplex structure of the set of feasible points of the design set. Thus the available iteration procedures for the unrestricted case are no longer applicable.

In this paper a penalty approach is suggested which transforms the restricted problem to the unrestricted case and allows the application of well-known algorithms such as the Fedorov-Wynn-type or the projected gradient procedure.     

金融发展、融资约束与战略性新兴产业发展

战略性新兴产业发展需要大量的资金投入,过高的外部融资成本已经成为阻碍战略性新兴产业发展的重要因素.促进战略性新兴产业发展,已经成为一个亟待解决的问题.文章利用2011-2014年七大战略性新兴产业422家上市公司15个季度的面板数据,分别考察了中国银行业与股票市场发展对战略性新兴产业发展的影响.实证结果显示,七大战略性新兴产业的融资约束具有异质性,节能环保产业、高端装备制造业和生物医药产业融资约束较小,新材料、新一代信息技术、新能源汽车和新能源产业具有更大的融资约束.进一步研究发现,金融发展缓解了战略性新兴产业的融资约束,其中股票市场发展较银行发展更能缓解战略性新兴产业的融资约束.     

组织特点、外部约束与行业协会能力

构建行业协会制度能力和服务能力测度指标,实证研究表明:协会组织特点、外部约束对于制度能力以及制度能力对于服务能力具有影响。组织特点中,协会兼职或离退休官员的存在不利于协会制度能力提高,尤其是离退休官员。收入虽然对制度能力没影响,但显著影响了服务能力。外部约束中,行业竞争不利于协会制度能力,也没有影响服务能力,反而容易诱发协会寻租活动。协会间竞争对于制度能力、服务能力都没有影响,但对寻租活动抑制效果显著。政策只对协会促进会员遵守规则的制度能力具有正向作用,对协会服务能力提升没有产生效果,仅减少了协会寻租可能。制度能力对于协会总体服务能力和正向服务能力都具有积极作用,而对于负向能力没有影响。     

减排约束下中国天然气供需安全评价:2006-2014年

为准确把握中国天然气供需安全状态,以2006-2014年的数据为样本,在模糊隶属度函数量化指标值的基础上,运用层次分析法(AHP)和熵值法确定指标权重,基于线性加权和函数计算均方根进行综合评价。结果表明:(1)中国天然气供需安全指数呈现"N形"波动,2006-2007年天然气供需安全指数上升。2007-2013年天然气供需安全指数年均下降1.7979。2013年以来天然气供需安全指数开始回升,天然气供需安全压力有所缓解。(2)天然气供应安全指数从2006年的17.5914下降到2013年的0.1556,峰谷差17.4359。天然气需求安全指数呈现"W形"波动。天然气市场安全指数相对稳定,2013年以来略有上升,天然气市场风险逐年下降。(3)天然气供需安全很大程度上取决于天然气供应是否安全。因此,建议从确保天然气稳定供应、提高天然气使用效率和降低市场风险方面采取措施,维护天然气供需安全。     

Accessibility of European museums to visitors with visual impairments

People who have visual impairments exceed 250 million persons worldwide and represent an important cohort of museum visitors. However, they experience many constraints to participation in daily life. Few studies analyse the accessibility of museums to visitors with visual impairments, and many are confined to a single museum and to a small set of strategies for improving accessibility. This article aims to identify a broad set of strategies to increase the accessibility of museums to visitors with visual impairments and analyse the accessibility of museums in four European cities. Conclusions and implications for policy-makers and museum managers, designed to promote the creation of inclusive museums, are presented.     

政府公共决策的规则限制

政府公共决策是一次利益再分配过程,由于＂经济人＂假设和政府的有限理性,政府公共决策权力时常被滥用,造成政府公共决策失误。制定完善的规则,规范政府公共决策权力,可以有效防止政府公共决策失误,使之解决民生之苦、反映民生之需、实现民生之乐。     

Land-use and environmental pressures resulting from current and future bioenergy crop expansion: A review

Recent energy and climate policies, particularly in the developed world, have increased demand for bioenergy² as an alternative, which has led to both direct and indirect land-use changes and an array of environmental and socio-economic concerns. A comprehensive understanding of the land-use dynamics of bioenergy crop production is essential for the development of sustainable bioenergy and land-use policies. In this paper, we review the patterns and dynamics of land-use change associated with bioenergy crops (hereafter referred to as ’bioenergy-driven land-use change’). The review focuses on four regions as the most prominent locations in which these patterns and changes occur: Brazil; Indonesia and Malaysia; the United States of America (U.S.A.); and the European Union (EU). The review confirms that bioenergy-driven land-use change has affected and will impact most severely on the ’land- and resource-abundant’ developing regions, such as Brazil, where economic development takes priority over sustainable land-use policies, and the enforcement capability is limited. Opportunities for more effective policy are available through the development of international climate change policy (e.g. REDD under the UNFCCC), and certification criteria for sustainable bioenergy products (e.g. EU RED). However, bioenergy produced from no and/or less land-using feedstocks (e.g. wastes and residues), and their associated technologies must be given higher priority to minimise bioenergy-driven land-use change and its negative impacts.