Ranking Crop Yield Models Using Out-of-Sample Likelihood Functions

There has been considerable debate regarding which probability distribution best represents crop yields. This study ranks six yield densities based on their out-of-sample forecasting performance. The forecasting ability for each density was ranked according to its likelihood function value when observed at out-of-sample observations. Results show that a semiparametric model offered by Goodwin and Ker best forecasts county average yields.     

土地利用变化动态模型的比较分析与评价

土地利用变化动态模型，已成为区域土地利用研究过程中重要的系统性方法。基于不同研究途径、研究目的和不同分析角度的动态模型具有不同的建模机理和解释功能，动态的、基于过程的模型比经验的、随机的和静态的模型更适合于预测土地利用变化的趋势。建立在不同空间分析基础之上的动态模型在表现形式和分析能力上有其不同的优缺点。本文通过对其优缺点的分析评价，提出了建模的新思路，为土地利用动态变化的研究方法作出新的尝试与探索。     

土地利用规划模型研究综述

研究目的：以服务土地利用规划编制为目标,针对区域土地利用规划模型研究进行系统回顾。研究方法：文献综述和比较分析法。研究结果：土地利用规划的核心是数量结构和空间布局的调整。作者从模拟与优化两个角度系统地分析了已有区域土地利用规划模型,论述了土地利用规划由传统单一数量结构研究向数量、空间协同研究的发展趋势,并探讨了这些模型在区域土地利用规划应用上的优势与不足。研究结论：基于GIS技术的 “自下而上”与“自上而下”双重耦合空间协同决策模式,是未来区域土地利用规划建模的发展方向,而关于国土空间多尺度转换机理解释是中国构建“多规合一”空间规划体系的关键所在。     

Stated and Inferred Attribute Attendance Models: A Comparison with Environmental Choice Experiments

There is increasing evidence that respondents to choice experiment surveys do not consider all attributes presented in the choice sets. Not accounting for this ‘attribute non‐attendance’ leads to biased parameter estimates, and hence biased estimates of willingness to pay. Various methods exist to account for non‐attendance in the analysis of choice data, with limited agreement as to which method is ‘best’. This paper compares modelling approaches that can account for non‐attendance, based on stated and inferred attribute non‐attendance. Respondents' stated non‐attendance is incorporated in the specification of multinomial and mixed logit models. Inference of non‐attendance is based on equality constrained latent class models. Results show that model fit is significantly improved when attribute non‐attendance is taken into account, and that welfare estimates are lower when incorporating non‐attendance. The inference based on equality constrained latent class models provides the best model fit. There is little concordance between stated and inferred non‐attendance, suggesting that respondents may not answer attendance statements truthfully.     

Graphical Illustration of Interaction Effects in Binary Choice Models: A Note

Graphing procedures for evaluating power or interaction terms in binary logit and probit models are illustrated in an application to hog producers’ decisions based on transaction cost economics’ hypothesised positive effect of the interaction of uncertainty and asset specificity on contract use. Results support the hypothesis, particularly for producers that are otherwise on the cusp (near the 50/50 probability) of choosing either contract or spot transactions based on their responses for other variables. Such insights may not be drawn without use of the demonstrated graphing procedures.     

国家--农民关系的新建构:以建国初期中南区的查田定产为中心

查田定产是国家与农民关系的一次新建构，它不仅影响到土改中阶级的划分，而且还使新生的国家全面掌拉了土地资源，确立了向农民征收农业税的依据，并为合作化运动中土地入社以及包工包产的推行奠定了基础。本文考察了建国初期中南区查田定产的推行概况、推行方法和组织领导机构，分析了查田定产的源起、影响以及不足。     

Going Beyond Impact Factors: A Survey‐based Journal Ranking by Agricultural Economists

A consistent and comprehensive ranking of journals relevant for agricultural economists cannot rely on impact factors for at least two major reasons: (i) the scientific database by Thomson Reuters, on which the standard impact factor is based, includes only a very limited number of relevant journals; (ii) the standard impact factor cannot be compared across research fields of different sizes. Survey‐based journal rankings may overcome these problems. We report on such a survey‐based ranking initiated by the Agricultural Economics Associations of Germany and Austria. Results of the ranking and a classification of journals, i.e. a rating, are provided for 160 selected journals. Scientific quality is assessed by an index based on the researchers’ perception of the quality standards of each journal and of the quality of its published articles. The survey‐based ranking allows a much more comprehensive and consistent ranking than the impact factor, as specific agricultural economics journals can be directly compared with neighbouring economic and interdisciplinary journals to which agricultural economists submit their work. The low impact factors of core agricultural economics journals are put into perspective. The scientific quality of the top agricultural economics journals is assessed as being rather high and above most of the relevant interdisciplinary journals from agricultural and food sciences that are typically characterised by higher impact factors. Agricultural economists’ perceptions on the scientific quality of the journals vary more across journals than perceptions of their relevance.     

A System Comparison Approach to Distinguish Two Nonseparable and Nonnested Agricultural Household Models

This study distinguishes two nonseparable agricultural household models for a self-employed farm household. One assumes heterogeneity of farm and nonfarm labor and a competitive market for nonfarm labor. The other assumes homogeneity of the two types of labor and a restricted market for nonfarm labor. We compare demand systems that are derived from them, which have different dependent variables and different numbers of equations. We apply a Cox-type test to compare these complicated nonnested systems. Results show clearly that the former is better for Japanese rice-farming households. Comparison of price elasticities for those models verifies the importance of that test.     

Modelling CAP Decoupling in the EU: A Comparison of Selected Simulation Models and Results

This article reviews ways of representing the effects of decoupling in the European Union (EU) on land allocation and production in eight selected simulation models (AGLINK, AG‐MEMOD, CAPRI, CAPSIM, ESIM, FAPRI, GOAL and GTAP). It then compares the simulated effects of decoupling and traces them back to the model specifications and parameter assumptions. In particular, roughage is not included in most models, so that changes in ruminant production are not necessarily consistent with the changes in fodder area. Models also differ in the extent to which they reflect the substitution possibilities in ruminant feeds. Notwithstanding the considerable differences in model types and specifications, all the studies considered here predict that as a result of decoupling, areas allocated to cereals (and silage maize) and beef and sheep production in the EU‐15 will decline, while fodder area will increase. Differences in the projections about pasture, oilseed and set‐aside areas can be attributed to different model or scenario specifications. The most important factor affecting the results is the extent to which the models assume that the Common Agricultural Policy (CAP) 2003 Reform (regarding Single Farm Payments) involves a substantial decoupling of support compared with the baseline (Agenda 2000) policy.     

Contextualized effects of Park access and usage on residential satisfaction: A spatial approach

The spatial implications of urban parks on people’s residential satisfaction are fueled by the desire to mitigate the rise of environmental injustice concerns in the developing world. While previous studies have examined the socio-spatial differentiation of park access and residential satisfaction, direct evidence on the role of park usage to play has been limited. This study shifts the focus from access to usage and quantitatively assess their associations with residential satisfaction. Our results quantify the evidence on the significant effects of park usage on residential satisfaction. Importantly, the association between park usage and residential satisfaction tends to be varied with local contextual amenities.     

The Potential for Nitrogen Abatement Trading in Agriculture: A Hypothetical Market Experiment

The effectiveness of nitrogen abatement trading as a policy measure relies on both heterogeneity in costs and environmental effectiveness across landscapes. Cost‐efficient implementation may therefore critically depend on spatial distributions of farm and farmer characteristics in water catchments. We use a spatially specific hypothetical market experiment to analyse the likelihood of farmers’ enrolment into nitrogen abatement trading contracts, and derive demand and supply functions for farmers’ nitrogen abatement. We find that farm characteristics influence both the decision whether to supply or purchase nitrogen abatement, as well as the amounts being traded. The derived demand and supply functions for farmers’ N abatement, using hypothetical market experiment data, can be used to reveal the variability in costs of abatement within a market. This provides valuable information to test potential trading schemes ex ante, to evaluate potential economic gains from policy implementation.     

国土资源管理决策模拟剧场与设计——以宅基地退出制度为例

传统的国土资源管理决策存在着定量分析手段缺乏、缺少系统性、关联性和标准化的问题。将政策分析理论与计算机技术引入国土资源管理领域,有机整合基础数据、分析模型和指标体系诸分析元素,建立国土资源管理决策模拟剧场系统,实现交互式决策智能分析系统构建,形成国土资源管理决策过程的标准化平台系统,可以有效解决传统决策方法的不足,降低决策成本。国土资源管理决策模拟剧场通过采取问题识别、问题概念化、模型数学化、比较与评价、反馈与执行等5个程式化步骤,具有较强的普适性,可广泛适用于国土资源管理决策与科研项目研究。     

中国食物供求分析及预测：基于贸易历史、国际比较和模型模拟分析的视角

研究分别从贸易历史、国际比较和模型模拟的视角对中国未来食物供求平衡状况进行了展望和模拟分析。(1)贸易历史的角度的经验结果显示,中国食物贸易净进口呈扩大态势;(2)中国大陆与日本、韩国及中国台湾地区的国际比较结果表明,中国未来粮食净进口可能会进一步扩大,尤其是对蛋白质来源食物需求可能会快速扩张;(3)基于中国食物供求局部均衡模型的模拟分析结果显示,中国谷物和油料作物供求平衡的缺口将不断扩大,主要谷物和油料作物的自给率将不断下降,同时,中国采取的玉米产业需求抑制政策对中国粮食供求平衡具有深远影响。综合以上不同视角的结果可以看出,要根本解决中国食物供求平衡问题,有必要建立食物安全与其他安全的综合安全观,实现4个方面的战略转变。即:第一,从重视确保数量向重视确保国内外资源战略转变,如签订粮食供给的政府间协议。第二,从重视总体粮食安全向重视主食安全、区域安全、运输安全(或航道安全)、流通和分配渠道安全、不同收入群体家庭食物安全转变。第三,从重视单一的食物安全向产业安全和质量安全转变。第四,从重视本国食物安全向全球视角转变。     

Integrated Management of Land Use Systems under Systemic Risks and Security Targets: A Stochastic Global Biosphere Management Model

Interdependencies among land use systems resemble a complex network connected through demand–supply relationships. Disruption of this network may catalyse systemic risks affecting food, energy, water and environmental security (FEWES) worldwide. We describe the conceptual development, expansion and practical application of a stochastic version of the Global Biosphere Management Model (GLOBIOM), used to assess competition for land use between agriculture, bioenergy and forestry at regional and global scales. In the stochastic version of the model, systemic risks of various kinds are explicitly covered and can be analysed and mitigated in all their interactions. While traditional deterministic scenario analysis produces sets of scenario‐dependent outcomes, stochastic GLOBIOM explicitly derives robust outcomes that leave the systems better‐off, independently of which scenario applies. Stochastic GLOBIOM is formulated as a stochastic optimisation model that is critical for evaluating portfolios of robust interdependent decisions: ex‐ante strategic decisions (production allocation, storage capacities) and ex‐post adaptive (demand, trading, storage control) decisions. As an example, the model is applied to the question of optimal storage facilities, as buffers for production shortfalls, to meet regional and global FEWES requirements when extreme events occur. Expected shortfalls and storage capacities have a close relationship with Value‐at‐Risk (VaR) and Conditional Value‐at‐Risk (CVaR) risk measures. A Value of Stochastic Solutions is calculated to illustrate the benefits of the stochastic over the deterministic model approach.