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Estimating Import Demand for Fresh Citrus. Gary D. Thompson Almuhanad Melhim The University of Arizona. Linda Calvin Economic Research Service. Why Study Import Demand?. Quantify Impacts of SPS Measures: Elasticities (Own- & Cross-Price) Flexibility Estimates
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Estimating Import Demand for Fresh Citrus Gary D. Thompson Almuhanad Melhim The University of Arizona Linda Calvin Economic Research Service
Why Study Import Demand? Quantify Impacts of SPS Measures: • Elasticities (Own- & Cross-Price) • Flexibility Estimates • Estimate Welfare of Impacts SPS
Characteristics of SPS Measures Clementines from Spain • Country- & Even Region-Specific • Date-Specific Aggregated Data Not Appropriate
U.S. Mandarin Imports, 2000-03 Spain Australia S. Africa Morocco Source: FATUS
Supply Side Drives Availability Clementines from Spain • Zero Import Quantity No Import Price Unobservable, Not Unobserved • Not Censoring; Partial Truncation: Missing Price & Quantity • Micro-Data Censoring Models Not Appropriate
Possible Approaches to Truncation • Incidental Truncation Sample selection is typically cross-sectional. Sample selection of import availability depends on agro-climatic factors (e.g. weather throughout the year)
Truncation & Demand Systems • Multiple selectivity equations + Demand system equations Cross-Sectional - Sequential Selectivity Models (Lahiri & Song)
Partial Truncation at Product Level Mandarins Oranges Tangerines
Selectivity Equations: Probit/Logit • Binary Regression: Dep. Vbl. = 0 if no imports = 1 if positive imports Exp. Vbls.: Temperature; Precipitation in Production Region
Marshallian Demand Equations • Incomplete Demand System LINQUAD: Weak integrability guarantees reliable elasticity and welfare measures.
Demand Equations + Truncation • Introduce Correction for Partial Truncation as Demographic Shifter in LINQUAD: Not just inverse Mills ratio Multivariate normal is maintained
Choice of Samples for Estimation 1. Consecutive Months Each Year • Oct. - Feb. Season; 1992-93 to 2002-03 • Aggregate Temporally to Eliminate Zero Quantities & Missing Prices • Semi-annual; 1989 - 2003
Uncompensated Elasticities, Sample Median Tangerine Mandarin Orange Tangerine -0.026 -4.016 0.463 Mandarin -0.006 -4.375 0.039 Orange 0.374 -0.670 -2.268 Sample: Monthly, Oct.-Feb., 1992 – 2003 (T = 55)
Uncompensated Elasticities, Sample Median Tangerine Mandarin Orange Tangerine -2.193 0.543 -0.134 Mandarin 0.020 -0.326 -0.463 Orange 0.133 -0.498 -0.101 Sample: Semi-annual, 1989 – 2003 (T = 30)
Own-Price Elasticity, Mandarins Oct 02 Oct 99 Oct 00 Oct 01 Suspension of Spanish Imports
Oct 02 Oct 99 Oct 00 Oct 01 Suspension of Spanish Imports Cross-Price Elasticity, Mand.-Orange
Correction for Truncation • Necessary for modeling seasonal availability of imports (or exports). • Yields reasonable, if highly variable, elasticity estimates. • Uses data readily available, e.g. FATUS, NOAA.
Future Work • Demand for Domestic & Imported Fresh Citrus • Apply to other specialty crops, e.g. asparagus, fresh tomatoes. • MLE or Non-Parametric Estimation