Gary D. Thompson - PowerPoint PPT Presentation

1 / 18
About This Presentation
Title:

Gary D. Thompson

Description:

Demand Equations + Truncation Introduce Correction for Partial Truncation as ... Precipitation in Production Region Marshallian Demand Equations ... – PowerPoint PPT presentation

Number of Views:80
Avg rating:3.0/5.0
Slides: 19
Provided by: GaryT157
Category:

less

Transcript and Presenter's Notes

Title: Gary D. Thompson


1
Estimating Import Demand for Fresh Citrus
  • Gary D. Thompson
  • Almuhanad Melhim
  • The University of Arizona

Linda Calvin Economic Research Service
2
Why Study Import Demand?
  • Quantify Impacts of SPS Measures
  • Elasticities (Own- Cross-Price)
  • Flexibility Estimates
  • Estimate Welfare of Impacts SPS

3
Characteristics of SPS Measures
  • Clementines from Spain
  • Country- Even Region-Specific
  • Date-Specific
  • ? Aggregated Data Not Appropriate

4
U.S. Mandarin Imports, 2000-03
Spain
Australia
S. Africa
Morocco
Source FATUS
5
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

6
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)

7
Truncation Demand Systems
  • Multiple selectivity equations Demand system
    equations
  • Cross-Sectional - Sequential Selectivity Models
    (Lahiri Song)

8
Partial Truncation at Product Level
Mandarins
Oranges
Tangerines
9
Selectivity Equations Probit/Logit
  • Binary Regression
  • Dep. Vbl. 0 if no imports
  • 1 if positive imports
  • Exp. Vbls. Temperature Precipitation
  • in Production Region

10
Marshallian Demand Equations
  • Incomplete Demand System
  • LINQUAD
  • Weak integrability guarantees reliable
    elasticity and welfare measures.

11
Demand Equations Truncation
  • Introduce Correction for Partial Truncation as
    Demographic Shifter in LINQUAD
  • ? Not just inverse Mills ratio
  • ? Multivariate normal is maintained

12
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

13
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)
14
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)
15
Own-Price Elasticity, Mandarins
Oct 02
Oct 99
Oct 00
Oct 01
Suspension of Spanish Imports
16
Cross-Price Elasticity, Mand.-Orange
17
Correction for Truncation
  1. Necessary for modeling seasonal availability of
    imports (or exports).
  2. Yields reasonable, if highly variable, elasticity
    estimates.
  3. Uses data readily available, e.g. FATUS, NOAA.

18
Future Work
  • Demand for Domestic Imported Fresh Citrus
  • Apply to other specialty crops, e.g. asparagus,
    fresh tomatoes.
  • MLE or Non-Parametric Estimation
Write a Comment
User Comments (0)
About PowerShow.com