USDA PRODUCTION FORECASTS FOR PORK, BEEF, AND BROILERS: AN EVALUATION

One-step-ahead forecasts of quarterly beef, pork, and poultry production are examined and evaluated based on traditional criteria for optimality-efficiency and unbiasedness-as well as their performance versus a univariate time-series model. However, traditional regression methodology for evaluating forecasts is avoided due to interpretive issues. Instead, an empirical framework focusing on forecast errors in employed. Results suggest USDA forecasts are unbiased, but generally not efficient. That is, they do not fully incorporate the information contained in past forecasts. Moreover, USDAÂ’'s predictions do not encompass all the information contained in forecasts generated by simple time-series models. Thus, practitioners who use the USDA forecasts may want to supplement them with time-series forecasts.Agribusiness,

On Theil's Errors

We take a fresh look at Theil's BLUS residuals and ask why they have gone out of fashion.All our simulation experiments indicate that tests based on BLUS residuals have higher power than those based on the more popular recursive residuals, even in those cases (structural breaks) where intuition would favour the recursive residuals.simulation;econometrics;statistics;comparison

The forward exchange rate as a predictor of the spot rate: The case of the B.L.E.U.. Some further results.

Exchange; Spot rate;

WHEN IS EXPENDITURE "EXOGENOUS" IN SEPARABLE DEMAND MODELS?

The separability hypothesis and expenditure as an exogenous variable in a system of conditional demands are analyzed. Expenditure cannot be weakly exogenous in a system of conditional demands specified as functions of the prices of the separable goods and total expenditure on those goods. Furthermore, expenditure is uncorrelated with the residuals of the conditional demand equations only when severe restrictions are satisfied. Therefore, expenditure will seldom be strictly exogenous. Econometric methods are presented for the consistent and efficient estimation of the unknown parameters when expenditures is correlated with the residuals and when it is not.Demand and Price Analysis,

The Global Joint Distribution of Income and Health

We investigate the evolution of global welfare in two dimensions: income per capita and life expectancy. First, we estimate the marginal distributions of income and life expectancy separately. More importantly, in contrast to previous univariate approaches, we consider income and life expectancy jointly and estimate their bivariate global distribution for 137 countries during 1970 - 2000. We reach several conclusions: the global joint distribution has evolved from a bimodal into a unimodal one, the evolution of the health distribution has preceded that of income, global inequality and poverty has decreased over time and the evolution of the global distribution has been welfare improving. Our decomposition of overall welfare indicates that global inequality would be underestimated if within-country inequality is not taken into account. Moreover, global inequality and poverty would be substantially underestimated if the dependence between the income and health distributions is ignored.Income; Health; Global Distribution; Inequality; Poverty

systemfit: A Package for Estimating Systems of Simultaneous Equations in R

Many statistical analyses (e.g., in econometrics, biostatistics and experimental design) are based on models containing systems of structurally related equations. The systemfit package provides the capability to estimate systems of linear equations within the R programming environment. For instance, this package can be used for "ordinary least squares" (OLS), "seemingly unrelated regression" (SUR), and the instrumental variable (IV) methods "two-stage least squares" (2SLS) and "three-stage least squares" (3SLS), where SUR and 3SLS estimations can optionally be iterated. Furthermore, the systemfit package provides tools for several statistical tests. It has been tested on a variety of datasets and its reliability is demonstrated.

The Global Joint Distribution of Income and Health

We investigate the evolution of global welfare in two dimensions: income per capita and life expectancy. First, we estimate the marginal distributions of income and life expectancy separately. More importantly, in contrast to previous univariate approaches, we consider income and life expectancy jointly and estimate their bivariate global distribution for 137 countries during 1970 - 2000. We reach several conclusions: the global joint distribution has evolved from a bimodal into a unimodal one, the evolution of the health distribution has preceded that of income, global inequality and poverty has decreased over time and the evolution of the global distribution has been welfare improving. Our decomposition of overall welfare indicates that global inequality would be underestimated if within-country inequality is not taken into account. Moreover, global inequality and poverty would be substantially underestimated if the dependence between the income and health distributions is ignored.income, health, global distribution, inequality, poverty

On Robust Alternatives to the Maximum Likelihood Estimators of a Linear Functional Relationship

This paper discusses a number of candidates for robust estimator TS of a simple linear functional relationship (SLFR). The classical maximum likelihood estimators of the SLFR can be affected by the presence of possible outliers. This is due to the fact that they are mean-based estimators. Some median-based estimator of the SLFR are examined. Among those considered Their-type estimators and the modified LI-norm estimator are found to be most robust (i.e insensitive to the outliers)