A nonparametric analysis of agricultural production behavior was conducted for each of the contiguous forty-eight states for the period 1956-82 under the joint hypothesis of profit maximization, convex technology, and nonregressive technical change. Tests were conducted in each state for profit maximization and for constant returns to scale. Although considerable variability was observed among states, measurement errors of magnitudes common in secondary data yielded test results fully consistent with the profit-maximization hypothesis in all states with complete output and input data. Copyright 1992 by MIT Press.

Subal C. Kumbhakar, Arunava Bhattacharyya, Price Distortions and Resource-Use Efficiency in Indian Agriculture: A Restricted Profit Function Approach, The Review of Economics and Statistics, Vol. 74, No. 2 (May, 1992), pp. 231-239

We characterize the conditions under which efficient portfolios put small weights on individual assets. These conditions bound mean returns with measures of average absolute covariability between assets. The bounds clarify the relationship between linear asset pricing models and well-diversified efficient portfolios. We argue that the extreme weightings in sample efficient portfolios are due to the dominance of a single factor in equity returns. This makes it easy to diversify on subsets to reduce residual risk, while weighting the subsets to reduce factor risk simultaneously. The latter involves taking extreme positions. This behavior seems unlikely to be attributable to sampling error.

The authors characterize the conditions under which efficient portfolios put small weights on individual assets. These conditions bound mean returns with measures of average absolute covariability between assets. The bounds clarify the relationship between linear asset pricing models and well-diversified efficient portfolios. The authors argue that the extreme weightings in sample efficient portfolios are due to the dominance of a single factor in equity returns. This makes it easy to diversify on subsets to reduce residual risk, while weighing the subsets to reduce factor risk simultaneously. The latter involves taking extreme positions. This behavior seems unlikely to be attributable to sampling error.

ABSTRACT We characterize the conditions under which efficient portfolios put small weights on individual assets. These conditions bound mean returns with measures of average absolute covariability between assets. The bounds clarify the relationship between linear asset pricing models and well‐diversified efficient portfolios. We argue that the extreme weightings in sample efficient portfolios are due to the dominance of a single factor in equity returns. This makes it easy to diversify on subsets to reduce residual risk, while weighting the subsets to reduce factor risk simultaneously. The latter involves taking extreme positions. This behavior seems unlikely to be attributable to sampling error.

The ability of planners in Poland and the U.S.S.R. to recognize and act to eliminate market disequilibrium in the markets for grain and meat is tested by means of an econometric model of grain and meat production, consumption, and trade. Planners' perceptions of excess demand for grain, meat, and foreign exchange are shown to influence production and trade decisions in a way that tends to reduce excess demand or supply. Nevertheless, the markets for grain, meat, and foreign exchange are shown to be characterized by excess demand or supply for much of the sample period. Copyright 1992 by MIT Press.