In recent years, there has been renewed interest in index number and aggregation theory, since the two previously divergent fields have been successfully unified. The underlying aggregator functions which are weakly separable subfunctions of utility and production functions, are the building blocks of economic theory, and the derivation of index numbers based upon their ability to track those building blocks is now called the "economic theory of index numbers." William Barnett, the coeditor of this volume, introduced modern economic index number theory into monetary economics. His merger of...