We wish to thank Georg Hasenkamp for valuable comments on an earlier draft of the manuscript and Steven Diamond for his kindness in reading the manu script and providing advice regarding the style of the exposition. We are also grateful to Miss Ingeborg Kasper for her careful typing of the manu script. Contents 1. Introduction 4 2. Price Indices Depending only on Prices 2. 1 Definition, Examples, Implications 4 2. 2 Characterizations of Pri e Indices 15 3. Price Indices Depending on Prices and Quantities 22 3. 1 Definition, Examples 23 3. 2 Fisher's System of Tests 29 3. 3 Implications and...