Precautionary Saving in the Small and in the Large.

The theory of precautionary saving is shown to be isomorphic to the Arrow-Pratt theory of risk aversion, making possible the application of a large body of knowledge about risk aversion to precautionary saving--and more generally, to the theory of optimal choice under risk. In particular, a measure of the strength of the precautionary saving motive analogous to the Arrow-Pratt measure of risk aversion is used to establish a number of new propositions about precautionary saving and to give a new interpretation of the Dreze-Modigliani substitution effect. Copyright 1990 by The Econometric Society.