The LeChatelier-Samuelson principle revisited

Within the context of a linear Leontief model, the LeChatelier-Samuelson principle examines the effects of an increase in some final demand on the output levels under the constraint that the production of certain goods is held at its original value. The principle states that the increase in any output is larger when fewer output levels are kept constant. The present paper discusses bounds for such incremental changes, second-order effects, the consequences on the markets for the products with restricted output levels, and generalizations of the original assumptions.I would like to thank two anonymous referees for their helpful comments.     

Project Evaluation and Uncertainty in Practice: A Statistical Analysis of Rate-of-Return Divergences of 1,015 World Bank Projects

This article analyzes the World Bank's experience with projectevaluation for a sample of 1,015 projects by comparing estimatedrates of return at appraisal with reestimated rates of returnwhen construction works are completed, usually 5 to 10 yearsafter appraisal. The analysis highlights the high degree ofuncertainty in project analysis. A wide range of variables hasbeen introduced to explain the observed divergence in appraisaland reestimated rates of return, but only a relatively smallpart of the divergence can be explained, even with the benefitof hindsight. Project analysis thus has to cope with a largedegree of uncertainty, which the traditional methods of projectevaluation and selection have not been able to reduce.     

On invariant parametric covariance families

Summary In this note we characterize all linear transformations of random vectors which are invariant for a given parametric covariance family. Two one-dimensional covariance families are discussed in detail.