Pooling consumption data from different countries for demand system estimation is attractive because it increases both sample size and therange of v ariation of relative prices and income. The major objection to pooling is that d ifferent countries may have different demand system parameters. This paper propo sed and estimates specifications that permit pooling while allowing both short-r un andlong-run demand systems to differ across countries. Using data from Belgi um, the United Kingdom, and the United States, the authors findthat, although p ooling was accepted for some pairs of countries and some specifications, it was rejected for most. They conclude that caution is appropriate in pooling internat ional consumption data.

A two-stage technology is a sequential production process that first uses pri mary inputs to produce intermediate inputs and then uses theintermediate inputs to produce final output. In this paper the authors show that two-stage technologies provide a general procedure for combining production functions or cost functions to obtain new specifications suitable for empirical production analysis. They investigate two new cost functions for which the input demand systemssatisfy global regularity conditions in a wide range of nondegenerate cases. Using six data sets, the authors estimate thesetwo input demand systems, both with and without imposing global regularity conditions, and find that one of them performs well.