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Crop Yield Distributions: A Reconciliation of Previous Research and Statistical Tests for Normality

Published by:
Online Location
https://ideas.repec.org/a/oup/revage/v31y2009i1p163-182..html
Publication date
09/06/2009
Language:
English
Type of Publication:
Studies
Focus Region:
Global
Focus Topic:
Agricultural Value Chains / Agri-Businesses
Type of Risk:
Biological & environmental
Type of Risk Managment Option:
Risk assessment
Commodity:
Crops
Author
Ardian Harri, Cumhur Erdem, Keith H. Coble, Thomas O. Knight
Organization
Agricultural and Applied Economics Association

This study revisits the large but inconclusive body of research on crop yield distributions. Using competing techniques across 3,852 crop and  county combinations some inconsistencies in previous studies  can be reconciled. We examine linear, polynomial, and ARIMA trend models. Normality tests are undertaken, with an implementable R-test and multivariate testing to account for spatial correlation. Empirical results show limited support for stochastic trends in yields. Results also show that normality rejection rates depend on the trend specification. Corn Belt corn and soybeans yields are negatively skewed while they tend to become more normal as one moves away from the Corn Belt.

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