The philosophy adopted and the literature coverage demonstrated owe mnuch to the assistance of: Thomas W. Calmus, Graduate School of Management and Business, University of Oregon; Karl Haiiser, Seminar fur Volkswirtschaftslehre, Universitdt Frankfurt/Al; J. C. L. Hulqkamp, International Bureau of Fiscal Documentation; and T. A. Kennedy, National Economic Development Office of the U.K. Errors of fact and interpretation are, of course, entirely of my doing.

Estimation and Inference in Econometrics, Russell Davidson and James G. MacKinnon, Oxford University Press, 1993, 874 + xx pages (Designated DM). A Course in Econometrics, Arthur S. Goldberger, Harvard University Press, 1991, 405 + xvii pages (Designated GO). Econometric Analysis, second edition, William H. Greene, Macmillan, New York, 1993, 791 + xxii pages (Designated GR). Learning and Practicing Econometrics, William E. Griffiths, R. Carter Hill, and George G. Judge, John Wiley, New York, 1993, 866 + xxv pages (Designated GHJ).

IN THIS PAPER the reader will find a review of econometric studies of investment in fixed capital. A review of these studies through 1953 was given in 1957 by J. Meyer and E. Kuh [86], and a detailed review through 1960 was presented by R. Eisner and R. H. Strotz in 1963 [36]. In this review we concentrate on recent research on time series of investment expenditures for individual firms and industries. Our point of departure is the flexible accelerator model of investment originated by H. B. Chenery [13, 1952] and L. M. Koyck [74, 1954]. In this model attention is focused on the time structure of the investment process. The desired level of capital is determined by longrun considerations. Changes in desired capital are transformed into actual investment expenditures by a geometric distributed lag fuinction-the specification of desired capital has been the subject of a wide variety of alternative theories; the alternative theories do agree on the validity of the flexible accelerator mechanism. Denoting the actual level of capital by K and the desired level by K+, capital is adjusted toward its desired level by a constant proportion of the difference between desired and actual capital,

Paul W. Rhode of University of Michigan and NBER reviews “Plagues upon the Earth: Disease and the Course of Human History” by Kyle Harper. The EconLit abstract of this book begins: “Explores the ways that human history has shaped disease ecology and pathogen evolution and how disease ecology and pathogen evolution have shaped human history in turn, detailing how the emergence, incidence, and consequences of disease in both individuals and populations are inseparable from a wider array of social and environmental factors.”

This essay reviews Networks and Markets, edited by James E. Rauch and Alessandra Casella. This book provides a useful vehicle for clarifying the main conceptual and operational issues facing the growing study of economic networks. Three types of networks are discussed: networks as concentrated or patterned exchange; as primordial relations; and, the most general, networks as structures of mutual orientation. An overview is provided of the challenges faced by research on the economic implications of three types of networks. The strengths and weaknesses of current research on economic networks are examined via a review of the contributions in the book.