The effect of small sample on optimal designs for logistic regression models

Asymptotic methods are commonly used in statistical inference for unknown parameters in binary data models. These methods are based on large sample theory, a condition which may be in conflict with small sample size and hence leads to poor results in the optimal designs theory. In this paper, we apply the second order expansions of the maximum likelihood estimator and derive a matrix formula for the mean square error (MSE) to obtain more precise optimal designs based on the MSE. Numerical results indicate the new optimal designs are more efficient than the optimal designs based on the information matrix.     

To what extent is social security spending associated with enhanced firm-level performance? A case study of SMEs in Indonesia

Although the relationship between social protection and enterprise performance is much debated in the literature, evidence is particularly limited in the case of small and medium-sized enterprises in developing economies. Using census data from 2010 to 2014, this article examines how the provision of social security influenced business performance in Indonesia. The author finds that increased social security spending of 10 per cent is associated with a per-worker revenue gain of up to 2 per cent. Moreover, profits are not found to decrease with increased social protection coverage, suggesting that increasing worker benefits may be a worthwhile business investment.     

基于违约鉴别能力组合赋权的小企业信用评级——基于小型工业企业样本数据的实证分析

信用评级是衡量债务违约的可能性,因此评级体系要有违约风险识别能力,能够将违约客户和非违约客户显著地区分开.通过逼近理想点的思路,构建多目标规划模型求解最优的组合权重,并对中国某区域性商业银行1 814笔小型工业企业贷款进行实证分析.本文的创新与特色一是以非违约企业的数据到正理想点的距离代数和最小为第一个目标函数,以违约企业的数据到负理想点的距离代数和最小为第二个目标函数,构建多目标非线性规划模型进行组合赋权,在满足了“非违约企业的评价得分越高、违约企业的评价得分越低”要求的目标下得到最优的组合赋权的权重系数,使赋权结果保证了评级模型能够将违约企业与非违约企业最大地区分开.改变了现有研究的组合赋权脱离评价目的的弊端,改变了现有研究中违约与非违约企业的评价得分存在大量重叠、对两类企业的区分能力低的弊端.二是通过检验“违约企业的信用得分是否显著小于非违约企业的信用得分”的J-T非参数检验,验证信用评价模型的合理性.改变现有研究忽略对信用评价模型的合理性进行验证的弊端.三是经过实证,发现本研究建立的组合赋权模型的违约鉴别能力(Z=5.546)要高于现有研究的两种常用组合赋权模型、即基于方差最大的组合赋权(Z=4.298)和基于偏差最小的组合赋权(Z=5.182)     

从主权国家的兴衰看权力博弈形态的转型

传统的国际关系理论,无论是现实主义、自由主义、建构主义还是科学行为主义理论,都是把主权国家抽象成一个统一的国际关系行为体。这一行为主体有一致的利益,也自然要有一致的对外政策目标和手段。在20世纪,尤其是在两次世界大战和冷战期间,这一概念抽象是非常准确的。但冷战结束以后,尤其是进入21世纪以后,这一概念抽象逐渐与国际关系的现实相违背。一方面,国家综合实力并不能直接转化为具体领域的竞争优势;另一方面,很多国家,包括超级大国在内,其对外政策的主要阻力可能不是所谓的竞争对手,而是其国内不同的利益集团。这导致传统的国际关系理论,从假设到概念和推理层面,都已经无法解释和预测今天的世界,而权力小博弈理论可以为认识多元复杂互动博弈时代的国际关系提供一个新的解释框架。     

A more powerful unconditional exact test of homogeneity for 2 × c contingency table analysis

The classical unconditional exact p-value test can be used to compare two multinomial distributions with small samples. This general hypothesis requires parameter estimation under the null which makes the test severely conservative. Similar property has been observed for Fisher's exact test with Barnard and Boschloo providing distinct adjustments that produce more powerful testing approaches. In this study, we develop a novel adjustment for the conservativeness of the unconditional multinomial exact p-value test that produces nominal type I error rate and increased power in comparison to all alternative approaches. We used a large simulation study to empirically estimate the 5th percentiles of the distributions of the p-values of the exact test over a range of scenarios and implemented a regression model to predict the values for two-sample multinomial settings. Our results show that the new test is uniformly more powerful than Fisher's, Barnard's, and Boschloo's tests with gains in power as large as several hundred percent in certain scenarios. Lastly, we provide a real-life data example where the unadjusted unconditional exact test wrongly fails to reject the null hypothesis and the corrected unconditional exact test rejects the null appropriately.     

Supply chain agility as an acclimatisation process to environmental uncertainty and organisational vulnerabilities: insights from British SMEs

Abstract

Even though supply chain agility (SCA) has been considered an essential concept in supply chain management (SCM) research, the way it is experienced and manifested, especially by small and medium-sized enterprises (SMEs), has received much less attention. Our purpose is to focus on SME organisational vulnerabilities in the context of increased environmental uncertainty, and explore how SCA is developed and applied by SMEs amid their vulnerabilities. By relying on insights from comparative case studies of three British SMEs, we examine SME SCA as an acclimatisation process and delve into SMEs’ experiences of facing environmental uncertainty while developing and applying SCA. Our findings highlight that organisational attitudes underlie how SMEs perceive environmental uncertainty, tackle organisational vulnerabilities and develop SCA as an acclimatisation process. Our findings also reveal that resource constraints, supply chain relationships, interorganisational power dynamics, and access to information play important roles in developing SCA.     

红色文化增进铸牢中华民族共同体意识的多维向度解析

红色文化是中国革命建设征程的历史凝结,补钙壮骨,通今溯源,与中华民族共同体意识有着严密的耦合逻辑。在政治上,红色文化有利于坚定中国共产党的领导,明晰铸牢中华民族共同体意识的政治前提;在经济上,红色文化彰显社会主义市场经济的民族互惠指向,夯实铸牢中华民族共同体意识的经济基础;在文化上,红色文化标注社会主义先进文化建设的中国底色,聚合中华民族共同体建设的文化动力;在社会上,红色文化促进各民族交往交流交融,提升铸牢中华民族共同体意识的社会认知;在生态上,红色文化有助于建立人与自然交响协奏的生命共同体,筑牢中华民族共同家园的生态底线。     

Information and communication technology adoption in micro and small firms: Can internet access improve labour productivity?

The rapid spread of information and communication technologies (ICT) may increase firms’ productivity with important consequences for job creation and for economic growth. This article contributes to this discussion by analysing the impact of internet adoption on labour productivity and the mechanisms shaping this relationship in Peruvian micro and small manufacturing firms over the period 2011–2013. The article estimates a reduced form where labour productivity is a function of internet adoption and other explanatory factors. Internet adoption is instrumented using a measure of the availability of financial opportunities for micro and small firms in Peru. Findings indicate that internet adoption: (a) increases firms’ labour productivity; (b) reallocates employment away from temporary administrative workers and non‐remunerated workers and expands employment of permanent production workers; (c) leads to the formalization of labour relationships, to the implementation of new organizational practices and to the improvement of training measures. While changes in employment and formalization of workers are linked to labour productivity gains, increases in training measures and organizational changes do not generate any additional productivity increase. Policies oriented to promote the adoption of ICT in micro and small firms can be beneficial to close the productivity gap with larger firms in Peru. Moreover, policies directed to the formalization of the workforce can provide an extra benefit, i.e. additional labour productivity gains in firms adopting the internet. Finally, policies oriented to the development of digital skills are also important to ease the re‐employment of those workers losing their jobs and the achievement of additional productivity gains that new organizational practices can provide.     

土地流转中为什么会形成大量小农复制

土地流转是实现规模化经营的前提之一,然而土地流转中却出现大量小农复制,从而影响土地流转的质量和效果。运用12省(自治区)2 553份农户问卷,详细分析土地流转中小农复制的现状及其形成原因。研究发现：(1)农户流转耕地面积不大,转入户流转面积20亩及以下的约占总转入户数的60.3％,转出户流转面积5亩及以下的约占总转出户数的74.38％,转出户中仍然经营土地的约占总转出户数的74％。(2)农业分工发达使生产更加方便、文化传统形成路径依赖、禀赋效应产生“价值幻觉”以及公共服务不健全使未来存在不确定性导致转出户流转部分土地。乡土社会限制土地流转范围和经营风险增加风险感知导致转入户流转小规模土地。