Cropland use,yields, and droughts: spatial data modeling for Burkina Faso and Niger

For countries with recurrent droughts, the design of drought impact mitigation measures could benefit from analyses of determinants of yields and prices of local crops at regional and district level. This study applies dynamic spatial panel data regression models to yields and prices of four major food crops across regions of Burkina Faso and Niger, over sample periods between 1984 and 2006. Results lend support to mainly simultaneous spatial spillovers, particularly for millet and cowpea prices and sorghum yields in Niger, and maize yields in Burkina Faso. After accounting for these effects, most crop yields are found to be weakly price‐responsive, as envisaged by a supply‐side geographical diffusion hypothesis. Seasonal rainfall elasticity estimates suggest that dominant food crops have slight advantage margins in terms of relative resilience to rainfall shortages. However, this result is to be weighed against low millet yields in Niger, and marked drops in sorghum yields during officially declared droughts in Burkina Faso.     

Digital Platforms and the Nature of the Firm

Abstract:

Digital platforms turn traditional approaches of the firm, which relied on the wage relation to explain the major difference between firm and market, upside down and underline the advantages of coordination through organization over coordination through market. This study aims to propose a definition of the firm able to integrate, besides the integrated firm, also hybrid forms such as networks of subcontractor/subcontracting firms as well as atypical forms such as digital platforms. By reactivating the firm-boundary problem, this article suggests putting valorization by labor at the heart of the firm’s decisions concerning integration. It suggests therefore a general definition of the firm as a techno-institutional center of capital valorization, provided that firms make profits by means of the appropriation of labor incorporated into their (productive, structural, intellectual) capital through institutional arrangements. By stressing the relation of production between the owners of the means of production and the direct producers, the approach of the firm supported here should allow to cover the different existing models of the firm, from the classical firm to hybrid models, around which the boundary debate has revolved, to digital platforms.     

企业家心智模式形成及其对企业发展的影响

心智模式（Mental models）是当前管理学界广泛关注的话题,有关企业家心智模式的讨论不论是在理论或实践领域都颇受关注。文章的主要目的是探讨企业家决策背后,所隐含的假设与信念——也就是企业家心智模式对企业发展的影响,并期望能提供一个新的完善企业家心智模式的途径。     

农地征收制度改革模式的解析及创新路径的选择

农地征收制度改革大致可以归纳为公益性农地征收和经营性集体建设用地直接入市两种模式。公益性农地征收制度改革模式是从发达国家移植过来的,改革面临着公共利益界定、合理补偿标准与公正征地程序确立等众多难题。集体建设用地直接入市是农民自发进行的制度创新,还有许多理论与法律障碍有待克服。两种农地征收制度改革模式的融合是城乡统筹发展的客观需要,中国农村渐进式的改革道路决定了两种农地征收制度改革模式也只能走渐进式融合的创新道路。     

Accounting for Negative,Zero and Positive Willingness to Pay for Landscape Change in a National Park

In contingent valuation, despite the fact that many externalities manifest themselves as costs to some and benefits to others, most studies restrict willingness to pay to being non‐negative. In this paper, we investigate the impact of allowing for negative, zero and positive preferences for prospective changes in woodland cover in two UK national parks, the Lake District and the Trossachs. An extended spike model is used to accomplish this. The policy implications of not allowing for negative values in terms of aggregate benefits are also investigated, by comparing the extended spike model with a simple spike making use of only zero and positive bids, and a model which considers positive bids only. We find that ignoring negative values over‐states the aggregate benefits of a woodland planting project by up to 44%.     

Spatiotemporal Modeling of Asian Citrus Canker Risks: Implications for Insurance and Indemnification Fund Models

Asiatic citrus canker is a disease that poses a significant hazard to commercial citrus production. This article examines spatiotemporal models of the risks of citrus canker transmission. Models evaluate risks and are used to price annual contracts, which would pay producers a prespecified indemnity in the event that their grove is found to be infected with canker. Implications for risk management policy are discussed.     

The tragedy of the commons: property rights and markets as solutions to resource and environmental problems

In one way or another, all environmental and natural resource problems associated with overexploitation or under provision of public goods, arise from incompletely defined and enforced property rights. As a result private decision makers do not consider or internalize social benefits and costs in their production or investment actions. The gap between private and social net returns results in externalities – harmful effects on third parties: overfishing, excessive air pollution, unwarranted extraction or diversion of ground or surface water, extreme depletion of oil and gas reservoirs. These situations are all examples of the 'The Tragedy of the Commons'. In this paper, I consider options for mitigating the losses of open access: common or group property regimes, government tax and regulation policy, more formal private property rights. I briefly summarize the problems and advantages of each option and describe why there has been move toward rights-based instruments in recent years: ITQ (individual transferable quotas), tradable emission permits, and private water rights. Introductions to the papers in the special issue follow.     

Ranking Crop Yield Models: A Comment

This comment discusses key specification issues that may have affected the performance and, therefore, the ranking of parametric models that were compared in a recent AJAE article. A procedure to obtain the most flexible parametric model specification possible, given the particular probability distribution function on which the model is based is presented. These specifications also allow for standardized and, therefore, more valid comparisons across parametric models that are based on different probability distributions. Finally, the comment cautions against generalization of the rankings in that AJAE article and recommends that these more flexible specifications be adopted in future comparisons and applications.     

北京文化创意产业集聚区建设研究

近年来,北京文化创意产业发展态势良好,成效显著,形成了一批特色鲜明的文化创意产业集聚区。本文在介绍北京文化创意产业集聚区总体发展情况的基础上,着重分析总结出北京文化创意产业集聚区建设发展的四种典型模式,并提出了进一步推进文化创意产业集聚区发展的对策与思路。