Browsing by Author "Driscoll, Paul"

Now showing 1 - 3 of 3
  • Thumbnail Image
    The effects of agricultural price policies on the funding of agricultural research: Chile 1960-1988
    Ortiz, Jaime (Virginia Tech, 1993)
    Chilean governments have simultaneously used a combination of price policies and expenditures on agricultural research in their efforts to enhance the performance of the agricultural sector. These two policy instruments, under changing political environments, have had important distributional implications for agricultural producers and consumers. Neglecting the interactions between these instruments may have distorted the measurement of research benefits. This dissertation examines the implications of agricultural price policies on the funding of public agricultural research. A political-economy framework allows for the interactions between producers and consumers/taxpayers in affecting policy formation. The welfare effects on each interest group are identified. Agricultural price policies and research expenditures on beef, wheat, milk, apples, and grapes are considered within a simultaneous system of supply, demand, price and research policy equations. Economic and political considerations determine the choice between direct price policies and public research expenditures. Results conform to theoretical expectations that the level and distribution of public research investments are affected by agricultural price policies. The implications derived from these results are that policies can be made more effective if decision-makers consider the complementarity or substitutability of these policy instruments. Agricultural production was influenced by direct price policies and by domestic agricultural research and foreign technology transfers. Publicly-sponsored agricultural research in Chile has had positive economic returns. The benefits to research, however, would have been larger if distorting price policies had not been present.
  • Thumbnail Image
    Misspecification testing in systems of equations
    Robertson, John Campbell (Virginia Tech, 1992)
    This dissertation is a set of related papers on the application of the "principle of statistical adequacy" to single and multi-equation econometric models. The first chapter lays out the intended scope of the dissertation and defines the principle of statistical adequacy. The second chapter reviews the formulation of tests of statistical adequacy for multivariate models, and describes the implementation of these tests. The first approach that is discussed is to select particular functions of the variables involved that should be orthogonal under the null hypothesis of no misspecification, and the sample analog of these functions is used as a basis for constructing misspecification tests. As an extension of this idea, it is argued that viewing the model in explicit probabilistic terms provides a basis for developing a set of orthogonality conditions that can be tested in terms of all the probabilistic assumptions underlying the model. The formulation of misspecification tests via auxiliary regressions using general polynomial functions and the implementation of these tests via a menu-driven econometric modeling computer program is described. The third chapter reports the results of an empirical application of the principle of Statistical adequacy to the modeling of inflation/unemployment trade-offs for the U.S. Using a Statistically adequate “reduced-form" as the basis, a number of competing theoretical models are considered. The use of graphical techniques and formal misspecification tests in determining the adequacy of the statistical model are emphasized. It is found that none of the competing theoretical explanations of aggregate labor market behavior are acceptable in terms of the over-identifying restrictions imposed or their own statistical adequacy. The final chapter is an example of how one might proceed when a specification failures the criteria of statistical adequacy. For U.S. interest rates, it is shown that linear-homoskedastic autoregessions do not adequately account for the leptokurtosis and non-linear temporal dependence in the data. Using the evidence provided by preliminary data analysis as a guide, the Student’s t autoregressive model with dynamic heteroskedasticity is estimated for the log differences in three interest rate series. The estimation and misspecification testing results suggest that the STAR model adequately accounts for the probabilistic features of the data: bell-shape symmetry; leptokurtosis; first and second-order temporal dependence. In contrast, a number of other heteroskedastic specifications are estimated, and found to be statistically inadequate.
  • Thumbnail Image
    System misspecification testing and structural-change in the demand for meats
    McGuirk, Anya; Driscoll, Paul; Alwang, Jeffrey R.; Huang, Huilin L. (Western Agricultural Economics Association, 1995-07)
    A misspecification testing strategy designed to ensure that the statistical assumptions underlying a system of equations are appropriate is outlined. The system tests take into account information in, and interactions between, all equations in the system and can be used in a wide variety of applications where systems of equations are estimated. The system testing approach is demonstrated by modeling U.S. consumer demand for meats. The example illustrates how the approach can be used to disentangle issues regarding structural change and other forms of model misspecification.