As with cascades in technology, cascades in the social sciences are not selfexplaining. In Britain, the economist A. D. Roy produced a mathematical analysis of portfolio selection (Roy 1952) that was contemporaneous with and similar to Markowitz's, while the statistician M. G. Kendall (1953) put forward the view of price changes as random walks. Unlike Markowitz's work, however, Roy's was not carried on by the equivalent of a Sharpe. Kendall's work was built upon, but in the United States, by Samuelson, not in the United Kingdom.

Donald MacKenzie, An Engine, Not a Camera, loc. 1094