Koo, Won W.

December, 1996

ACREAGE RESPONSES TO EXPECTED REVENUES AND PRICE RISK FOR MINOR OILSEEDS AND PROGRAM CROPS IN THE NORTHERN PLAINS

By: Krause, Mark A.; Koo, Won W.
Wheat, barely, flaxseed, and oilseed sunflower acreage respond to different economic variables. Wheat and barely acreage must be divided among program-complying, program-planted, and nonprogram-planted acreage because these categories respond to different variables and respond to own expected-revenue and price-risk variables in opposite ways. Flaxseed, sunflower, and nonprogram-planted acreage of wheat and barley have highly significant, positive responses to their own expected revenue and negative responses to their own-price risk. Flaxseed and sunflower acreage have been more responsive to their lagged values than to expected revenues for wheat.
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July, 1995

PROGRAM AND NONPROGRAM WHEAT ACREAGE RESPONSES TO PRICES AND RISK

By: Krause, Mark A.; Lee, Jung-Hee; Koo, Won W.
Wheat acreage responses to expected wheat price and price risk are reversed for program and nonprogram-planted acreage in the northern plains, central plains, southern plains, and U.S. Expected wheat price has a strong negative effect on program-complying wheat acreage. Government support prices have a positive effect on program-complying and program-planted acreage. Price risk has a positive effect on program-complying wheat acreage and a negative effect on nonprogram-planted acreage. Estimated price elasticities are higher than in studies where risk was ignored.
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December, 1994

JAPANESE MEAT IMPORT DEMAND ESTIMATION WITH THE SOURCE DIFFERENTIATED AIDS MODEL

By: Yang, Seung-Ryong; Koo, Won W.
A source differentiated AIDS model is specified to estimate Japanese meat import demand. Block separability and product aggregation are rejected at conventional levels of significance. The model with the block substitutability restriction explains more than 95% of data variation. The empirical results indicate that the U.S. has the largest potential for beef exports to Japan. Taiwan is in a strong position in the pork market, and Thailand and China are strong in the poultry market. The U.S. competes with Canada and Taiwan in the pork market, but the competition between Taiwan and European countries is the strongest in the market. The U.S. competes with Thailand in the poultry market, where the U.S. is the most vulnerable.
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December, 1993

MONETARY IMPACTS ON PRICES IN THE SHORT AND LONG RUN: FURTHER RESULTS FOR THE UNITED STATES

By: Choe, Young Chan; Koo, Won W.
This study examines the long-run neutrality of money and the short-run dynamics of farm and nonfarm prices to the monetary shock, using Johansen's approach. Results find a long-run equality of prices, but not neutrality. In the short-run, farm prices adjust faster than nonfarm prices to a monetary shock.
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July, 1992

HETEROSKEDASTICITY IN CROP YIELD MODELS

By: Yang, Seung-Ryong; Koo, Won W.; Wilson, William W.
This study examines three alternative models of correcting for heteroskedasticity in wheat yield: the time trend variance, the GARCH, and an econometric model that includes the potential sources of heteroskedasticity. Nonnested test results suggest that modeling the sources of heteroskedasticity is the preferred procedure. Including potential sources of heteroskedasticity as explanatory variables removed the heteroskedasticity in the sample wheat yields. The results also suggest that the GARCH specification is a promising model of correcting for heteroskedasticity when the sources cannot be identified. The time trend variance model alone may misspecify the true variance structure.
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