. Gravity and Comparative Advantage: Estimation of Trade Elasticities for the Agricultural Sector Kari E.R. Heerman, Economic Research Service, USDA Ian Sheldon, Ohio State University 2018 IATRC Annual Meeting Whistler, BC Canada July 25-27, 2018 The analysis and views expressed are the authors’ and do not represent the views of the Economic Research Service or USDA.
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.Gravity and Comparative Advantage:
Estimation of Trade Elasticities for theAgricultural Sector
Kari E.R. Heerman, Economic Research Service, USDAIan Sheldon, Ohio State University
2018 IATRC Annual Meeting
Whistler, BC CanadaJuly 25-27, 2018
The analysis and views expressed are the authors’ and do not represent theviews of the Economic Research Service or USDA.
Heerman and Sheldon July 25-27, 2018
Introduction
Systematic Heterogeneity (SH) Gravity Model
• Tailored to fundamental features of agriculture & sub-sectors
⇒ Allows systematic influences on within-sector specialization
• Standard gravity models impose restrictive elasticities
– Arkolakis, Costinot and Rodriguez-Clare (2012), Adao,Costinot and Donaldson (2017)
– “Independence of Irrelevant Exporters” (IIE) property
• Relative demand is unaffected by third-country costs
• An illustration...
Heerman and Sheldon July 25-27, 2018
Example: U.S. raises tariffs on Costa Rican agriculture
Other 9.1%
Beef 2.8% Fruit, nes
3.2%
Melons 7.5%
Coffee 10.7%
Pineapples 16.8%
Bananas 40.8%
US Ag Imports: Costa Rica
Standard gravity predicts equal increases in trade flows for any two
exporters with the same share of the US ag market
Heerman and Sheldon July 25-27, 2018
Example: U.S. raises tariffs on Costa Rican agriculture
Other 9.1%
Beef 2.8% Fruit, nes
3.2%
Melons 7.5%
Coffee 10.7%
Pineapples 16.8%
Bananas 40.8%
US Ag Imports: Costa Rica
Other 5.0% Coffee 2.6%
Mangoes 2.8%
Fruit, Nes 3.7%
Cocoa 4.7%
Plantains 5%
Bananas 71.4%
Ecuador US Ag Market Share = .001%
Other 4.2%
Eggplants 2.4%
Green Chiles
& Peppers 44.1%
Tomatoes 45.8%
The Netherlands: US Ag Market Share = .001%
Heerman and Sheldon July 25-27, 2018
Roadmap
• Structural model overview
• Specification of econometric model
• Estimation
• Selected results
• Conclusion
Heerman and Sheldon July 25-27, 2018
Structural Model Overview
Heerman and Sheldon July 25-27, 2018
About the Model
Environment
• I countries engaged in bilateral agricultural trade
– Exporter indexed by i
– Importer index by n
• A continuum of products indexed by j
• Production technology is heterogeneous across products
– Climate and land characteristics influence which productshave the highest productivity
• All markets are perfectly competitive
• Trade occurs as buyers look for the lowest price
Heerman and Sheldon July 25-27, 2018
Model Overview
Production Technology Country i , product j technology
qi (j) = zi (j)× (Niβi (ai (j)Li )
1−βi )αi Qi1−αi
• Input bundle: labor (Ni ), land (Li ), intermediates Qi
• zi (j) Technological productivity-enhancing Frechet r.v.
Fi (z) = exp{−Tiz−θ}
– Ti drives average technological productivity in country i
– θ drives dispersion of technological productivity
– Independently distributed across products
• E.g., coffee
• ai (j) is deterministic variable representing land productivity
Heerman and Sheldon July 25-27, 2018
Model Overview
Production Technology Country i , product j technology
qi (j) = zi (j)× (Niβi (ai (j)Li )
1−βi )αi Qi1−αi
• ai (j) is deterministic variable representing land productivity
– Value reflects the coincidence of product requirements andcountry ecological characteristics
• E.g., coffee
– Country-specific parametric density, independent of zi (j)
Heerman and Sheldon July 25-27, 2018
Trade
Heerman and Sheldon July 25-27, 2018
Model Overview
Comparative Advantage Probability country i has comparativeadvantage in product j in market n
πni (j) =Ti (ai (j)ciτni (j))−θ
N∑l=1
Tl(al(j)clτnl(j))−θ
• Probability country i price offer is lowest in market n
– ci is the cost of an input bundle
• τni (j) ≥ 1 is exporter i ’s cost to export products to market n
– Deterministic variable with parametric density
– Independent of zi (j) and ai (j)
Heerman and Sheldon July 25-27, 2018
Model Overview
Market Share Exporter i share in country n agriculture expenditure
πni =
∫Ti (aiciτni )
−θ
N∑l=1
Tl(alclτnl)−θdFan(a)dFτ n(τ )
• This is the structural equation from which the SH gravitymodel is derived
– Fan(a) is the distribution of an = [a1, ..., aI ] across allproducts consumed in market n
– Fτ n(τ ) is the distribution of τ = [τn1, ..., τnI ] across allproducts consumed in market n
Heerman and Sheldon July 25-27, 2018
Specification
Heerman and Sheldon July 25-27, 2018
Random Coefficients Logit Specification
• Average productivity and input bundle cost as in EK
lnTi − θlnci ≡ Si
– Country fixed effect
Heerman and Sheldon July 25-27, 2018
Random Coefficients Logit Specification
Land Productivityln(ai (j)) ≡ Xiδ(j)
• Exporter Characteristics
– Xi =[aLi elvi tropi tempi bori
]• ali - (log) arable land per capita, World Bank• elvi share of rural land at high altitude, CIESIN• tropi - share of land in tropical climate zone, GTAP
Heerman and Sheldon July 25-27, 2018
Random Coefficients Logit Specification
Land Productivityln(ai (j)) ≡ Xiδ(j)
δ(j) = δ + (E(j)Λ)′ + (νE (j)ΣE )′
• Product characteristics
– “Observable” production requirements
• E(j) =[alw(j) elv(j) trop(j) temp(j) bor(j)
]– Ex., trop(j) - tropical climate intensity of cultivation
– Trade-weighted averages of country characteristics