Empirical demand systems that do not impose unreasonable restrictions on preferences are typically non-linear. We show, however, that all popular systems possess the property of conditional linearity. A computationally attractive iterated linear least squares estimator (ILLE) is proposed for...

This paper develops a new concept of separability with overlapping groups. This is shown to provide a useful empirical and theoretical framework for investigating the grouping of goods and prices. It is a generalisation of weak separability in which goods are allowed to enter more than one group...