No abstract

Rates of increase in the number of parameters of a Fourier factor demand system that imply asymptotically normal elasticity estimates are characterized. The main technical problem in achieving this characterization is caused by the fact that the eigenvalues of the sample sum of squares and cross products matrix of the generalized least squares estimator are not bounded from below. This problem is addressed by establishing a uniform strong law with rate for the eigenvalues of this matrix so as to relate them to the eigenvalues of the expected sum of squares and cross products matrix. Because the minimum eigenvalue of the latter matrix considered as a function of the number of parameters decreases faster than any polynomial, the rate at which parameters may increase is slower than any fractional power of the sample size.

No abstract

No abstract

The aim of this paper is to use DEA models to evaluate sustainability in agriculture. Several variables are taken into account and the resulting efficiency is measured by comparison. The performance of family farms is analysed here (variables: farmed area, work force, and production). As agricultural sustainability depends on the maintenance of systems of production for long periods of time, the models were run for the years of 1986 and 2002. Tiered DEA models were used to group farmers in sustainability categories. Non-parametric regression models were used to identify the factors affecting the efficiency measurements. All the results indicate that the majority of the farmers increased their efficiency along the time. These improvements may support the existence of sustainability.