A note on the projection properties of Hadamard matrices obtained by the first Payley construction

We show that the projections on four factors of an arbitrary orthogonal array of strength 2 allow the estimation of main effects and two-factor interactions when all other effects are assumed to be zero, if those projections satisfy the bounds given by Weils theorem. The only exceptions are the Hadamard matrices of orders 16 and 24. A consequence is again the estimability of main effects and two-factor interactions for the projections on four factors of the first Payley construction for arbitrary run size.     

On the evolutionary edge of altruism: a game-theoretic proof of Hamilton’s rule for a simple case of siblings

We offer a game-theoretic proof of Hamiltons rule for the spread of altruism. For a simple case of siblings, we show that the rule can be derived as the outcome of a one-shot prisoners dilemma game between siblings.JEL Classification: A13, C70, D64Correspondence to: Oded Stark, ZEF, University of Bonn, Walter-Flex-Strasse 3, 53113 Bonn, GermanyWe are indebted to an anonymous referee and to Uwe Cantner for helpful comments and suggestions. Partial financial support from the National Institute on Aging (grant RO1-AG13037) and from the Humboldt Foundation is gratefully acknowledged.     

Voting in assemblies of shareholders and incomplete markets

Summary. An economy with two dates is considered, one state at the first date and a finite number of states at the last date. Shareholders determine production plans by voting - one share, one vote - and at -majority stable stock market equilibria, alternative production plans are supported by at most percent of the shareholders. It is shown that a -majority stable stock market equilibrium exists if where S is the number of states at the last date and J is the number of firms. Moreover, an example shows that -majority stable stock market equilibria need not exist for smaller s.Received: 23 December 2002, Revised: 14 June 2004, JEL Classification Numbers: D21, D52, D71, G39. Correspondence to: Hervé CrésThe authors are grateful to an anonymous referee for helpful comments and suggestions. Financial support from the Danish Research Councils and hospitality of HEC is gratefully acknowledged by Mich Tvede and support from Fondation HEC is gratefully acknowledged by Hervé Crés.     

The effect of a magazine’s free digital content on its print circulation: Cannibalization or complementarity?

We examine how offering digital content affects demand for print magazines. Using a searchable website archive, we measure the digital content offered by a sample of US consumer magazines from 1996 to 2001. We find strong evidence that digital content cannibalizes print sales. On average, a magazine’s print circulation declines about 3–4% when it offers a website. However, the effect varies with the type of digital content offered. Offering digital access to the entire contents of the current print magazine reduces print sales by about 9%. We find no evidence that digital content complements print magazines. These results are robust to including controls for unobserved magazine, category, and time effects, as well as controls for the impact of contemporaneous price changes and other factors.     

数字中国"与西部大开发

面对新世纪，结合我国国情，阐述了构建“数字中国”的重要意义和作用，并就建设和发展“数字中国”提出了一些建议，特别是指出在西部大开发进程中应充分利用现有的信息资源，实现西部经济的跨越式发展。     

论图书馆数字信息资源建设

我国图书馆数字信息资源建设还存在着宏观上缺乏协调机制和规范，资金投入缺乏制度保障，特色数字信息资源的构建力度不够，数字信息资源的建设缺乏实用性，人员素质偏低等问题。相应的解决对策是加强图书馆数字信息资源建设的宏观协调和规范管理，完善政府相关政策加大资金投入，进一步优化文献信息资源结构，形成特色数字信息资源，根据用户需求构建数字信息资源，以增强实用性，提高图书馆员信息素质，为数字信息资源建设提供能力保障。     

数字信息资源的发展与图书馆期刊工作

本文分析了数字信息资源的发展给图书馆期刊工作带来的积极作用和压力，并探讨了数字信息资源的发展与改进图书馆期刊工作对策。     

城镇数字化地产评估系统及应用

城镇数字化地产评估系统是以“城市土地定级估价综合模型”作为主要评估方法 ,针对中小城镇地产评估的实际情况 ,基于Map/info平台 ,将多种应用程序集成而开发出来的。经实际使用 ,该系统操作简便 ,经济适用。     

疫情危机与商业银行数字化对策研究

疫情危机的发生导致社会经济链条断裂,供应链流通受阻,并不断向上下游和其他节点传导,引爆诸多潜在的风险点,对社会经济产生巨大负面影响。本文以商业银行为例,研究疫情危机对商业银行的影响和管理危机的对策。研究表明,疫情危机的发生既是对社会经济秩序的一种破坏,同时也会在应对危机过程中催生出一些新的行业、产业或经营模式的变化。面对疫情危机,数字化不仅仅是商业银行应对危机的有效手段,更是商业银行转型升级的新方向。全面推进数字化对于其他行业应对疫情危机同样具有示范和借鉴意义。     

The measurement of corporate portfolio strategy: analysis of the content validity of related diversification indexes

Measures developed for the analysis of corporate diversification have become fundamental to a broad range of strategy research. This paper examines the content validity of the two most widely used continuous measures of related diversification—the related component of the entropy index and the concentric index—and raises fundamental questions about their validity as indicators of portfolio relatedness. These questions are not driven by the use of SIC data for estimation of the indexes; they involve validity problems intrinsic to the construction of the measures. The related component of entropy and the concentric index are sensitive to features of corporate portfolio composition that may not be directly linked to portfolio relatedness. These sensitivities can create important ambiguities in strategy research. Copyright © 2002 John Wiley & Sons, Ltd.