On the Distribution of Crop Yields: Does the Central Limit Theorem Apply?
In this paper we take issue with the applicability of the central limit theorem (CLT) on aggregate crop yields. We argue that even after correcting for the effects of spatial dependence, systemic heterogeneities and risk factors, aggregation does not necessarily lead to normality. We show that aggregation is also likely to lead to nonnormal distributions, which exhibit both skewness and excess kurtosis. In particular, we consider the case in which the number of summands is not constant but varies with time, which corresponds to the empirically relevant situation where the number of acres used for cultivation of a particular crop exhibits substantial variation over time. In this case, the CLT is not applicable while the limit theorems for random sums of random variables, which apply, predict that the limiting distribution of the sum is not normal and depends on the postulated distribution of the number of summands. Using data from aggregate US states crop yields, we provide empirical support regarding the deviation of aggregate crops yields from normality.
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- Blattberg, Robert C & Gonedes, Nicholas J, 1974. "A Comparison of the Stable and Student Distributions as Statistical Models for Stock Prices," The Journal of Business, University of Chicago Press, vol. 47(2), pages 244-80, April.
- Weninger, Quinn & Just, Richard E., 1999.
"Are Crop Yields Normally Distributed?,"
Staff General Research Papers
5064, Iowa State University, Department of Economics.
- Zanini, Fabio C. & Sherrick, Bruce J. & Schnitkey, Gary D. & Irwin, Scott H., 2001.
"Crop Insurance Valuation Under Alternative Yield Distributions,"
2001 Conference, April 23-24, 2001, St. Louis, Missouri
18953, NCR-134 Conference on Applied Commodity Price Analysis, Forecasting, and Market Risk Management.
- Bruce J. Sherrick & Fabio C. Zanini & Gary D. Schnitkey & Scott H. Irwin, 2004. "Crop Insurance Valuation under Alternative Yield Distributions," American Journal of Agricultural Economics, Agricultural and Applied Economics Association, vol. 86(2), pages 406-419.
- Hennessy, David A., 2009.
"Crop Yield Skewness and the Normal Distribution,"
Journal of Agricultural and Resource Economics,
Western Agricultural Economics Association, vol. 34(1), April.
- Barry K. Goodwin & Alan P. Ker, 1998. "Nonparametric Estimation of Crop Yield Distributions: Implications for Rating Group-Risk Crop Insurance Contracts," American Journal of Agricultural Economics, Agricultural and Applied Economics Association, vol. 80(1), pages 139-153.
- Joseph Atwood & Saleem Shaik & Myles Watts, 2003. "Are Crop Yields Normally Distributed? A Reexamination," American Journal of Agricultural Economics, Agricultural and Applied Economics Association, vol. 85(4), pages 888-901.
- Clark, Peter K, 1973. "A Subordinated Stochastic Process Model with Finite Variance for Speculative Prices," Econometrica, Econometric Society, vol. 41(1), pages 135-55, January.
- Alan P. Ker & Barry K. Goodwin, 2000. "Nonparametric Estimation of Crop Insurance Rates Revisited," American Journal of Agricultural Economics, Agricultural and Applied Economics Association, vol. 82(2), pages 463-478.
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