by Peter J. D. Wiles Professor Emeritus University of London There are two sorts of writers of prefaces: the obliging and the disobliging. Surely Peter MiMlyi knows where to place me in this taxonomy. For the most part I write my own irrelevant opinions, but there was one act of gross interference: my insistence on a point he had already quietly made, the greater stability of the production of consumer goods under Communism even of food, if we exclude bad harvests. The many Marxist and some other scholars who wrote about Dr. Mihby Peter J. D. Wiles Professor Emeritus University of London There are two sorts of writers of prefaces: the obliging and the disobliging. Surely Peter MiMlyi knows where to place me in this taxonomy. For the most part I write my own irrelevant opinions, but there was one act of gross interference: my insistence on a point he had already quietly made, the greater stability of the production of consumer goods under Communism even of food, if we exclude bad harvests. The many Marxist and some other scholars who wrote about Dr. Mihand Summary of Main Points.- 1. General Framework.- 1.1 Three schools.- 1.2 Cycles or fluctuations ?.- 1.3 Socialism.- 1.4 Statistical definition of investments.- 1.5 Theory and statistical reality.- 1.6 The relevance of cycle models.- 1.7 Formalised summary.- 2. Three Schools of Thought.- 2.1 Control theory models.- 2.1.1 The complexity argument.- 2.1.2 Election cycles in Soviet-type economies.- 2.1.3 Replacement cycles and the role of large investment projects.- 2.2 Endogenous models.- 2.2.1 The periodic nature of planning.- 2.2.2 The investment commitment model.- 2.3 Common elements.- 2.4 Exogenous models.- 2.4.1 The role of politics.- 2.4.2 Fluctuations due to planning errors.- 2.4.3 Fluctuations due to campaigns.- 2.4.4 The cliffs edge thesis.- 2.4.5 Investment cycles or business cycles ?.- 2.4.6 GINV: target or control variable ?.- 2.4.7 The paradigm of bureaucratic regularity.- 3. Measurement of Investment Fluclc(