3,015 works, 150 years of economic thought. Each one summarized and searchable, with cited passages inside.
Can stock-price changes look random while price levels retain a structure that a random walk cannot explain? In this 1962 research memorandum, Clive W. J. Granger and Oskar Morgenstern use spectral analysis to separate movements at different time scales. Their distinctive finding is not a dependable market cycle, but a methodological tension: differencing prices can obscure slow fluctuations, making a model appear more adequate than it is. Short-run movements largely support the random-walk benchmark; longer-run variation exceeds its predictions. Yet weak seasonal and business-cycle components offer little support for cyclical investment rules. The memorandum shows readers why evidence against a simple model need not yield a usable forecast—and how statistical transformations can conceal precisely the features an inquiry seeks to understand.