启研学社由知名学者担任学术顾问，高校师生与企研数据科学团队联合组建，以大数据资源及相关技术助力中国学术与智库研究为宗旨的研究组织。团队当前的主要目标是挖掘经济社会大数据资源在学术和智库领域的应用价值，开展学术大数据治理研究，以及探索大数据分析技术融入中国经济社会研究的可行进路。
本周，启研学社的小伙伴给大家细数了农经领域的权威国际期刊（点此回顾），其中排名第一的便是American Journal of Agricultural Economics。受篇幅所限，今天先为大家带来 AJAE 2020年10月第5期文章摘要及翻译中的6篇，余下部分，将在明天继续为读者朋友介绍。
【1】Anukriti, S., et al. (2020). "Curse of the Mummy‐ji: The Influence of Mothers‐in‐Law on Women in India†." American Journal of Agricultural Economics 102(5): 1328-1351.
Restrictive social norms and strategic constraints imposed by family members can limit women's access to and benefits from social networks, especially in patrilocal societies. We characterize young married women's social networks in rural India and analyze how inter‐generational power dynamics within the household affect their network formation. Using primary data from Uttar Pradesh, we show that co‐residence with the mother‐in‐law is negatively correlated with her daughter‐in‐law's mobility and ability to form social connections outside the household, especially those related to health, fertility, and family planning. Our findings suggest that the mother‐in‐law's restrictive behavior is potentially driven by the misalignment of fertility preferences between the mother‐in‐law and the daughter‐in‐law. The lack of peers outside the household lowers the daughter‐in‐law's likelihood of visiting a family planning clinic and of using modern contraception. We find suggestive evidence that this is because outside peers (a) positively influence daughter‐in‐law's beliefs about the social acceptability of family planning and (b) enable the daughter‐in‐law to overcome mobility constraints by accompanying her to health clinics.家庭成员强加的限制性社会规范和约束会限制妇女进入社交网络并从中受益，特别是在父系社会中（patrilocal societies）。我们描述了印度农村已婚青年妇女社会网络的特点，并分析了家庭内的代际权力动态如何影响她们的网络形成。使用印度北方邦（Uttar Pradesh）的原始数据，我们发现，儿媳与婆婆同住会降低她们的流动性和在家庭外建立社会关系的能力，尤其是与健康、生育（fertility）和计划生育（family planning）有关的社会关系。我们的研究结果表明，婆婆的限制行为有可能是由婆媳之间的生育偏好错位（misalignment）造成的。家庭外缺少同龄人陪伴和交流，降低了儿媳去计划生育诊所就诊和通过现代避孕方法避孕的可能性。有证据表明，家庭外的同伴会积极影响儿媳对计划生育的社会认可度的看法并通过陪伴儿媳到卫生所就诊，克服她们的流动性限制。
【2】Arellano‐Gonzalez, J. and F. C. Moore (2020). "Intertemporal Arbitrage of Water and Long‐Term Agricultural Investments: Drought, Groundwater Banking, and Perennial Cropping Decisions in California." American Journal of Agricultural Economics 102(5): 1368-1382.
In arid areas, irrigation water is an essential input into agricultural production. However, rainfall and, correspondingly, surface water supplies are often highly variable, creating uncertainty over the value of long‐term, water‐dependent investments in these cropping systems. Moreover, climate change is expected to increase both crop water requirements and the variability of seasonal rainfall, meaning the constraints imposed by variable water supplies are likely to grow in cost as climate change progresses. In this setting, storing water in wet years for use in dry years is valuable. In particular, it would be expected to increase the value of perennial crops, which require large up‐front investments that pay off gradually over the life of the tree. We first show, in a simple theoretical model, that given the timing of returns to investments in perennial crops, there is always some level of drought risk above which annual crops will be preferred to perennials. We then demonstrate this effect empirically using a unique institutional setting in which access to a relatively new form of water storage, groundwater banking, effectively created spatial variation in drought risk between irrigation districts in Kern County, California. Using a 22‐year dataset of individual cropping decisions, we provide evidence that access to a large groundwater banking project, the Kern Water Bank, increased the rate at which farmers switched from lower value annual crops such as wheat and alfalfa into high‐value perennial nut crops, primarily almonds and pistachio.
水资源和农业长期投资的跨期套利（Intertemporal Arbitrage）：加利福尼亚州的干旱、地下水库和多年生作物（Perennial Cropping）种植决策
灌溉用水是一项重要的农业生产投入，然而在干旱地区，降雨量和地表水供应量往往变化很大，这给投资于依赖水的、生长周期长的作物的收益造成了不确定性。此外，气候变化可能会增加作物对水的需求量，以及提高季节性降雨量的波动，即随着气候变化，水资源的不确定供应所带来的约束可能会导致成本增加。在这种情况下，在雨水充沛的年份储水以供旱年是划算的，尤其是对多年生植物而言，这种做法会极大提高它们的投资回报——多年生作物需要大量的前期（up‐front）投资，这些投资会在作物的整个生命周期中逐步得到回报。首先，我们将多年生作物的投资回收年限和对应的干旱风险纳入到理论模型中，发现当干旱风险超过一定水平时，投资一年生作物将优于投资多年生作物。然后，我们通过设置一个独特的制度环境对上述效应进行实证检验，在这个环境中，我们利用一种相对较新的储水形式--地下水库，有效地造成了加州克恩县各灌溉区之间干旱风险的空间差异。利用22年的个人种植决策数据集，我们提供了如下证据：大型地下水库（克恩水库）的存在，提高了农民从种植小麦和苜蓿等价值较低的一年生作物转向种植高价值的多年生坚果作物（主要是杏仁和开心果）的速度。
【3】Belay, D. G., et al. (2020). "A Montero Auction Mechanism to Regulate Antimicrobial Consumption in Agriculture." American Journal of Agricultural Economics 102(5): 1448-1467.
Livestock production accounts for the lion's share of antibiotic consumption worldwide, and the sector is a significant contributor to antimicrobial resistance (AMR). Because farmers do not consider the contribution of their individual consumption of antibiotics to AMR, regulations are necessary to ensure optimal use. However, previously suggested regulatory instruments are either inefficient or nearly impossible to implement, mainly because they fail to address the information asymmetry that exists between farmers and regulators. In this article, we customize and suggest an efficient and incentive‐compatible regulatory instrument for antibiotic use based on the Montero auction mechanism (2008). We analytically and empirically demonstrate that the proposed auction mechanism is welfare improving as compared to current regulations. For the empirical analysis, we calibrate a simulation model for the Danish livestock sector based on farm accounts data for different types of livestock farms and combine it with calibrated demand functions for antibiotic allowances and a calibrated damage function. Based on the simulation results and the implementation of systems such as the Danish VETSTAT (a detailed accounting of farmers' antibiotic use), we anticipate that the proposed mechanism can be effectively used in the future.
规范农业抗菌素（Antimicrobial）消费的蒙特罗拍卖机制（Montero Auction Mechanism）
畜牧业是全球抗生素消费最多的行业，它被视为造成抗生素耐药性的罪魁祸首。因为养殖户往往没有意识到考虑到抗生素的大量使用将提高抗菌素耐药性，所以有必要对抗生素的使用进行监管。然而，以前提出的监管手段因无法解决养殖户和监管者之间存在的信息不对称（information asymmetry）问题，要么实施效率低下，要么几乎不可能实施。本文基于蒙特罗拍卖机制（2008），提出了一种效率与激励相容的抗生素使用监管手段。并且我们通过理论分析和实证分析证明了与现行法规相比，本文提出的拍卖机制更能够改善福利。在实证分析中，我们根据不同类型畜禽养殖场（livestock farms）账户数据，对丹麦畜牧业的模拟模型进行了校准，并将其与校准的抗生素补贴需求函数和校准的损害函数相结合。根据模拟结果和丹麦VETSTAT（详细统计农户抗生素使用情况）等系统的实施情况，我们估计本文所提出的机制在未来能得到有效利用。
【4】Belissa, T., et al. (2020). "Effects of Index Insurance on Demand and Supply of Credit: Evidence from Ethiopia." American Journal of Agricultural Economics 102(5): 1511-1531.
Index‐based insurance offers a climate risk management strategy that can benefit the poor. This article focuses on whether adopting index insurance improves access to financial markets and reduces credit rationing, using empirical analyses focused on Ethiopia. With different identification strategies, including a newly developed method that leverages the varying availability of index insurance across areas, the authors control for potential selection biases by forecasting potential insurance adopters; they apply a cross‐sectional double‐difference method. Credit rationing can take the form of either supply‐side quantity rationing, in which case potential borrowers who need credit are involuntarily excluded from the credit market, or demand‐side rationing, such that borrowers self‐select and voluntarily withdraw to avoid transaction costs and threats to their collateral. By differentiating supply‐side and demand‐side forms and employing a direct elicitation method to determine credit rationing status, this study reveals that 38% of sample households are credit constrained. The preferred estimation techniques suggest that index insurance significantly reduces supply‐side rationing.
指数保险对信贷需求和供给的影响：来自埃塞俄比亚的证据
基于指数的保险提供了一种可以使穷人受益的气候风险管理策略。本文主要针对埃塞俄比亚进行实证分析，重点研究采用指数保险是否可以改善金融市场准入现状并减少信贷配给（credit rationing）。作者采用不同的识别策略，包括一种新开发的方法——利用各地区指数保险不同的可得性，作者通过预测潜在的保险购买者来控制潜在的选择偏差；本文运用了截面双差法（cross‐sectional double‐difference method）。信贷配给可以采取供应方定量配给的形式，在这种情况下，需要信贷的潜在借款人会被非自愿地排除在信贷市场之外；也可以采取需求方配给的形式，即借款人自我选择并自愿退出，以避免交易成本和对其抵押物（collateral）的威胁。本研究通过区分供给方和需求方、采用直接诱导法确定信贷配给状况，发现38%的样本家庭存在信贷约束。首选的估计技术表明，指数保险显著降低了供应方配给。
【5】Bigelow, D. P. and T. Kuethe (2020). "A Tale of Two Borders: Use‐Value Assessment, Land Development, and Irrigation Investment." American Journal of Agricultural Economics 102(5): 1404-1424.
Since 1960, all 50 states in the US have adopted some form of preferential tax treatment for farmland. These provisions often take the form of use‐value assessment, where farmland is taxed on the basis of its value in agricultural production, as opposed to its full market value. While the main goal of use‐value assessment is to slow the conversion of farmland to non‐agricultural uses, other channels of influence are also possible, such as those stemming from reinvestment of foregone tax expenses. Despite its widespread nature, there is little empirical evidence pertaining to the influence of use‐value assessment on land‐use or investment decisions. Using a postmatching difference‐in‐differences framework, we exploit the temporal and spatial discontinuities surrounding the adoption of use‐value assessment in Kansas in 1989 to measure how use‐value assessment affected plot‐level land development and irrigation investment decisions. The results of our analysis indicate that, as intended, the use‐value assessment policy curtailed development in the Kansas City metropolitan area. Evidence regarding the potential investment‐spurring effects of use‐value assessment is more mixed, suggesting that farmers may have increased irrigation in some areas because of use‐value assessment‐induced tax savings.自1960年以来美国50个州都对农田采取了某种形式的优惠税收待遇（preferential tax treatment）。这些规定通常采取使用价值评估（use‐value assessment）的形式，即根据农田在农业生产中的价值来征税，而不是根据其全部市场价值来征税。虽然使用价值评估主要是为了减缓农田向非农业用地的转换，但也有可能造成其他的影响，比如原先（省下来）的税费再投资产生的影响。尽管使用价值评估被广泛应用，但关于使用价值评估对土地使用或投资决策的影响研究很少。我们运用匹配后双重差分框架，利用1989年在堪萨斯州使用价值评估的时间和空间间断点，来衡量使用价值评估对地块层面的土地开发和灌溉投资决策的影响。如预期一致，我们的分析结果表明，使用价值评估政策抑制了（curtailed）堪萨斯城都市区的发展。关于使用价值评估对投资的潜在刺激作用更为复杂，本文的证据表明：农民可能因为采用使用价值评估的方法可以节税，所以增加了某些地区的灌溉。
【6】Çakır, M., et al. (2020). "Rural Food Retailing and Independent Grocery Retailer Exits." American Journal of Agricultural Economics 102(5): 1352-1367.
We investigate the food retailing landscape and the exit of independent grocery stores in rural America using U.S. NETS data. Our paper makes several contributions that could potentially help the agenda for future research and public policy. We begin by documenting local concentration trends in food retailing and how they change across rural and urban markets from 1990 to 2015. Then, we conduct two event studies to examine how entry by a large chain is associated with the local market concentration and independent grocery retailer (IGR) exits. Last, we document the IGR exit rate in rural markets for a period of twenty‐five years and investigate its determinants in a regression framework. Our results show that market concentration in food retailing has increased since 1990, but the increasing trend after the Great Recession of 2008 is particularly noticeable. The local concentration differs substantially by the urban status of markets. Focusing on rural markets, we show that entry by a large food retailer is associated with higher market concentration and the decreasing number of IGRs. We also find that the annual average IGR exit rate is around 6.6% during the study period. The IGRs that are younger that operate in relatively more competitive markets, and that face entry by a large chain, are more likely to exit. Also, IGR rates are higher in markets with lower median income and higher poverty rates. We discuss how our results can potentially inform policies on sustainable rural development, food access, and food insecurity in rural communities.我们运用美国NETS数据研究了美国农村地区的食品零售布局和独立杂货店的退出情况。我们的论文做出了一些贡献，这些贡献可能有助于未来研究和公共政策的制定。首先，我们记录了食品零售业的地方集中度趋势，以及从1990年到2015年食品零售业在城乡市场中的变化情况。然后，我们进行了两项研究去检验大型连锁店的进入与当地市场集中度和独立杂货零售商（IGR）的退出的关系。最后，我们记录了农村市场二十五年的IGR退出率，并在回归框架下研究了其决定因素。结果表明，自1990年以来，食品零售业的市场集中度有所提高，而且2008年经济大萧条后，上升趋势尤为明显。因市场的城市地位不同，地方集聚度有较大差异。集中于农村市场，我们发现大型食品零售商的进入与较高的市场集中度和IGR数量的减少有关。并且我们发现，在研究期间IGR的年均退出率约为6.6%。在相对竞争更激烈的市场中运作、并且面临大型连锁企业进入的年轻的IGR退出的可能性更大。另外，在收入中位数较低、贫困率较高的市场中，IGR的退出率也较高。我们讨论了我们的结果如何为农村可持续发展、粮食供应和农村社区粮食不安全等政策制定提供参考。
【7】Chambers, R. G., et al. (2020). "The Millennium Droughts and Australian Agricultural Productivity Performance: A Nonparametric Analysis." American Journal of Agricultural Economics 102(5): 1383-1403.
With the turn of the century, Australian agricultural productivity growth slowed dramatically. We investigate the connection between this slowdown and climatic factors by comparing regional‐level growth patterns before and after the advent of the Australian Millennium Droughts. The analysis incorporates climatic variates directly into the productivity accounting framework to reflect the stochastic nature of agricultural production, and measured productivity growth is decomposed into four components: technological change, weather‐related change, input‐scale adjustment, and diffusion (adaptation). Nonparametric productivity measurement and statistical techniques are used to quantify and examine the patterns of the observed productivity slowdown. The analysis suggests that the primary determinant of the slowdown is not a slowdown in technological innovation but climatic‐related changes in the pattern and rate of diffusion of technological advances.随着世纪之交，澳大利亚农业生产率增长急剧放缓。我们通过比较澳大利亚千年干旱出现前后区域层面的增长模式，研究这种放缓与气候因素之间的联系。本文将气候变数直接纳入生产率核算框架，以反映农业生产的随机性，并将测算得到的生产率增长分解为四个部分：技术变化、与天气相关的变化、投入规模调整和扩散（适应）。同时本文采用非参数生产力测算和统计技术，对生产率放缓模式进行量化和研究。本文分析表明，农业生产率增长放缓的主要决定因素并不在于技术创新变缓，而在于技术进步模式和扩散速度下的气候变化。
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翻译丨张惠茹
审核 | 大杰（陈煌杰）、焖肉（沈梦露）
排版编辑丨青酱
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