AJAE《美国农业经济学期刊》2022年第104卷第3期目录及摘要

全文链接：

https://onlinelibrary.wiley.com/toc/14678276/2022/104/3

Causality in structural vector autoregressions: Science or sorcery?

Dalia Ghanem, Aaron Smith

Blame it on the rain: Rainfall variability, consumption smoothing, and subjective well-being in rural Ethiopia

Yonas Alem, Jonathan Colmer

Somebody's watching me! Impacts of the spot check list program in U.S. crop insurance

Sungkwol Park, Xiaoyong Zheng, Roderick M. Rejesus, Barry K. Goodwin

The effect of prior appropriation water rights on land-allocation decisions in irrigated agriculture

Kelly M. Cobourn, Xinde Ji, Siân Mooney, Neil F. Crescenti

Nonparametric segmentation methods: Applications of unsupervised machine learning and revealed preference

Joey Blumberg, Gary Thompson

Rural broadband speeds and business startup rates

Steven Deller, Brian Whitacre, Tessa Conroy

The impact of the Affordable Care Act Medicaid expansions on agricultural workers' health insurance coverage, medical care utilization, and labor supply

Amy M. G. Kandilov, Ivan T. Kandilov

Online shopping and the healthfulness of grocery purchases

Katherine Harris-Lagoudakis

Mitigating stigma associated with recycled water

Sean F. Ellis, Olesya M. Savchenko, Kent D. Messer

Weather shocks, traders' expectations, and food prices

Marco Letta, Pierluigi Montalbano, Guillaume Pierre

Regulating ingredients in sin goods

Paul Calcott

Preserving local biodiversity through crop diversification

Eric Strobl

Causality in structural vector autoregressions: Science or sorcery?

Dalia Ghanem    Aaron Smith

Abstract：This paper presents the structural vector autoregression (SVAR) as a method for estimating dynamic causal effects in agricultural and resource economics. We have a pedagogical purpose; we aim the presentation at economists trained primarily in microeconometrics. The SVAR is a model of a system, whereas a reduced-form microeconometric study aims to estimate the causal effect of one variable on another. The system approach produces estimates of a complete set of causal relationships among the variables, but it requires strong assumptions to do so. We explain these assumptions and describe similarities and differences with the classical instrumental variables (IV) model. We demonstrate that the population analogue of the Wald IV estimator for a particular causal effect is identical to the ratio of two impulse responses from an SVAR. We further demonstrate that incorrect identification assumptions about some components of the SVAR do not necessarily invalidate the estimated causal effects of other components. We present an SVAR analysis of global supply and demand for agricultural commodities, which was previously examined using IV. We illustrate the additional economic insights that the SVAR reveals, and we articulate the additional assumptions upon which those insights rest.

Blame it on the rain: Rainfall variability, consumption smoothing, and subjective well-being in rural Ethiopia

Yonas Alem    Jonathan Colmer

Abstract：How does income uncertainty affect individual well-being? Combining individual-level panel data from rural Ethiopia with high-resolution meteorological data, we estimate that mean-preserving increases in rainfall variability are associated with reductions in objective consumption and subjective well-being. Mediation analysis suggests that the estimated reduction in consumption does not fully explain the total effect on individual well-being. Increased rainfall variability also has a large direct effect on individual well-being. These findings suggest that the gains from further consumption smoothing are likely greater than estimates based solely on observed consumption fluctuations.

Somebody's watching me! Impacts of the spot check list program in U.S. crop insurance

Sungkwol Park    Xiaoyong Zheng    Roderick M. Rejesus    Barry K. Goodwin

Abstract：The “Spot Check List” (SCL) is an important tool developed to help detect and deter fraud, waste, and abuse in the U.S. crop insurance program. This article examines whether the SCL program affects the extent of crop insurance losses and provides insights into the effectiveness of this program. Using proprietary, county-level SCL data and panel data econometric procedures (which control for both observable and unobservable confounding factors), we find evidence that counties with more producers included in the SCL tend to have better actuarial performance (i.e., lower indemnity payment amounts) after these producers are informed about their listing on the SCL. In addition, the county-level SCL effects tend to last for a couple more years beyond the initial year these SCL producers were informed of their listing. These results indicate that the SCL procedure has a notable impact on crop insurance losses and is a valuable tool for maintaining integrity of the program.

The effect of prior appropriation water rights on land-allocation decisions in irrigated agriculture

Kelly M. Cobourn    Xinde Ji    Siân Mooney    Neil F. Crescenti

Abstract：The doctrine of prior appropriation, which administers water rights based on seniority, may introduce heterogeneity in the risk of a water shortage among otherwise similar agricultural irrigators. We develop a theoretical model that describes how farmers with differing seniority in water rights adjust land-allocation decisions in response to an anticipated change in water deliveries. Using a fine-scale dataset of spatially referenced surface water rights for Idaho's Eastern Snake River Plain, we find evidence that irrigators with differing water rights make systematically different land-allocation decisions, and that farmers with the most junior (least secure) water rights are most responsive to an expected water shortage. These irrigators adapt to anticipated dry conditions by increasing land fallowed and planting a less profitable, drought-resilient mix of crops. Relatively dry growing season conditions exacerbate the potential for prior appropriation to introduce inefficiencies by driving a divergence in resource-use decisions between otherwise similar irrigators with differing water rights.

Nonparametric segmentation methods: Applications of unsupervised machine learning and revealed preference

Joey Blumberg    Gary Thompson

Abstract：Many recent efforts by econometricians have focused on supervised machine learning techniques to aid in empirical studies using experimental data. By contrast, this article explores the merits of unsupervised machine learning algorithms for informing ex ante policy design using observational data. We examine the extent to which groups of consumers with differing responses to economic incentives can be identified in a context of fruit and vegetable demand. Two classes of nonparametric algorithms—revealed preference and unsupervised machine learning—are compared for segmenting households in the National Consumer Panel. Nonlinear almost-ideal demand models are estimated for all segments to determine which methods group households into segments with different expenditure and price elasticities. In-sample comparisons and out-of-sample prediction results indicate methods using price-quantity data alone—without demographic, geographic, or other variables—perform better at segmenting households into groups with sizeable differences in price and expenditure responsiveness. These segmentation results suggest considerable heterogeneity in household purchasing behavior of fruits and vegetables.

Rural broadband speeds and business startup rates

Steven Deller    Brian Whitacre    Tessa Conroy

Abstract：Using 2014 U.S. nonmetropolitan county-level data, we explore the relationship between broadband speeds and business startup rates. Rural development policy discussions have presumed that access to broadband has become a necessary, although not sufficient, condition for economic growth and development. The relationship between broadband access on business startups, which are vital to local economic vibrancy, may be key to understanding the link between broadband and growth. In this study, we explore how qualitative features of broadband influence startup rates across different types of industries. To refine our insights into these relationships, we look at broadband by speed (both download and upload coverage across four speed categories). We also consider the importance of mobile broadband availability, which is often ignored in empirical studies. Because of the presence of spatial dependency within the data and the fact that data on business startup rates is limited to the minority of establishments that have employees, we use a Bayesian spatial Tobit estimator. After controlling for a host of variables likely to influence economic growth, we find that broadband coverage does matter and that download speeds tend to be more important than upload speeds. This pattern holds for mobile coverage as well. Perhaps the most important finding is that the results vary across business type: what matters for new businesses in one industry may not matter for other industry classifications. In the end, our results reaffirm the policy notion that access to broadband is increasingly relevant to rural entrepreneurship.

The impact of the Affordable Care Act Medicaid expansions on agricultural workers' health insurance coverage, medical care utilization, and labor supply

Amy M. G. Kandilov    Ivan T. Kandilov

Abstract：Nearly 30% of documented agricultural workers, that is, those who are authorized to work in the U.S. and may be eligible for government-sponsored Medicaid coverage, lacked health insurance coverage in 2016. We estimate the impact of the 2014 state-level Medicaid expansions that were part of the Affordable Care Act (ACA) on farm workers' health insurance coverage, health care utilization, and labor supply. Using confidential individual-level data from the National Agricultural Workers Survey (NAWS) for the decade between 2007 and 2016, we employ a difference-in-differences econometric model to compare workers in states that expanded Medicaid in 2014 to workers in states that did not. We find that, following the ACA Medicaid expansions, documented agricultural workers experience a 12-percentage point (24%) increase in the likelihood of having health insurance, which is entirely driven by an increase in the likelihood of having a government-sponsored health insurance plan. We do not detect a decrease in private (employer-sponsored or worker-acquired) health insurance coverage. Further, we find no evidence that the ACA Medicaid expansions led to a decline in farm workers' labor supply; in fact, our results imply that there was a small increase in farm workers' hours. In a number of falsification tests, we also show that the Medicaid expansions do not appear to have an impact on undocumented (unauthorized) farm workers' health care utilization, and there was no increase in Medicaid payments for health services among this group of farm workers who were largely ineligible for Medicaid.

Online shopping and the healthfulness of grocery purchases

Katherine Harris-Lagoudakis

Abstract：This paper utilizes novel household panel data to analyze the effect of online grocery shopping on the healthfulness of grocery purchases. We utilize variation in the timing that an online shopping service was introduced as a source of exogenous variation in the decision to shop online. Relative to pre-online service averages, our estimates indicate that online shopping baskets allocate 10.2 (21.7)% more of the total spending (calories) toward healthful product categories and are 10.1% more nutrient dense. We also evaluate the effect of online shopping on the monthly aggregate (in-store and online) basket. Average treatment effects for the treated (ATT) indicate a 2.3% decline in the sugar/sweet/candy budget share upon the introduction of the online shopping service; however, summary measures of healthfulness do not illustrate robust changes at the monthly level.

Mitigating stigma associated with recycled water

Sean F. Ellis    Olesya M. Savchenko    Kent D. Messer

Abstract：Stigmatization of water and food products can constrain markets and prevent the implementation of scientifically safe solutions to environmental problems, such as water scarcity. Recycled water can be a cost-effective, dependable, and safe solution to water shortages. However, consumers generally either require a large reduction in price to purchase products made with recycled water or reject such products outright. If emerging sustainable agricultural technologies, such as recycled water, are to be used to address growing water shortages worldwide, policymakers, water managers, and industry stakeholders must identify effective strategies for mitigating the stigma associated with recycled water. Using field experiments involving 1420 adult participants, we test the effectiveness of two stigma-mitigating techniques. We also demonstrate a novel twist to the collection of representative samples in non-hypothetical field experimental settings and then compare the results to a more traditional field experiment that recruited participants at large public gatherings. The analysis of these two different samples suggests a common finding: passing recycled water through a natural barrier, such as an aquifer, removes the stigma consumers would otherwise attach to it. We also find that the trophic level an organism occupies in the food chain influences stigmatizing behavior. The greater the steps in the food chain between an organism and the use of recycled water, the less it is stigmatized by consumers. These results have important implications for efforts to promote large-scale potable and non-potable water recycling projects and the use of recycled water in the agricultural industry.

Weather shocks, traders' expectations, and food prices

Marco Letta    Pierluigi Montalbano    Guillaume Pierre

Abstract：The empirical literature on the impacts of weather shocks on agricultural prices typically explores post-harvest price dynamics rather than pre-harvest ones. Inspired by the intra-annual competitive storage theory, we empirically investigate the role of weather news in traders' anticipations on pre-harvest price fluctuations in India's local markets. Using a panel of district-level monthly wholesale food prices from 2004 to 2017, we leverage the time lag between a weather anomaly and the corresponding supply shock to isolate price reactions caused by changes in expectations. We find that drought conditions significantly increase food prices during the growing period, that is before any harvest failure has materialized. These results suggest that markets respond immediately to expected supply shortfalls by updating their beliefs and adapting accordingly and that the expectation channel accounts for a substantial share of supply-side food price shocks. A direct comparison with the effects of the same weather anomalies on the prices of the first harvest month reveals that expectations anticipate more than 80% of the total price impact.

Regulating ingredients in sin goods

Paul Calcott

Abstract：If consumption of unhealthy food is excessive, then a policymaker might respond with a corrective tax. However, she might supplement the tax with a regulatory standard that limits the concentration of an unhealthy ingredient. A tax can restore social efficiency without supplemental regulation if all of four of the following conditions are satisfied: The tax is nutrient specific, the market structure is perfect competition, the magnitude of the distortion is the same across all consumers, and consumers do not react to the tax by substituting to untaxed foods that also have unhealthy ingredients. But if any of these conditions are not met, then there can be benefits to supplementing a corrective tax with a standard.

Preserving local biodiversity through crop diversification

Eric Strobl

Abstract：Using the case study of birds and food crops, we investigate whether diversifying crop production can enhance preservation of local biodiversity. To this end we combine annual bird survey data, high resolution land use data, and phylogenetic trees to create a landscape level panel data set covering the conterminous United States for over a decade. Our econometric analysis shows that greater local food crop hetereogeneity increases local avian diversity, although this is spatially limited. Supplementary county level data provides evidence that more food crop diversity is unlikely to be at the cost of lower revenues.

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编辑：代安澜

审核：龙文进