Although a considerable theoretical literature and a number of small scale applications of techniques for dealing with uncertainty in policy analysis and policy focused research have been around for a couple of decades, larger applications to major policy problems are a more recent phenomenon. Because many of the ideas and techniques involved are new, even to members of the technical community, their introduction into policy circles has been uneven and accompanied by a variety of mistakes and false starts. Nevertheless, there have now been a number of important applications, and several U. S. federal agencies have become seriously committed to the continued development and use of these techniques. For readers unfamiliar with these developments we briefly motivate the discussions that follow with three case examples that involve techniques for incorporating an explicit treatment of uncertainty in (1) estimates of the safety of light-water nuclear reactors; (2) the regulatory analysis of common (“criteria”) air pollutants; and (3) estimates of the probable impacts on the ozone layer of continued release of chlorofluorocarbons.

Reactor Safety

One of the earliest large-scale studies to employ a formal treatment of uncertainty was the Reactor Safety Study, NUREG-75/014 (WASH-1400), generally known as the “Rasmussen report” (Rasmussen et al., 1975).