The PHS guidelines contain a set of recommendations for conducting cost-effectiveness studies (Gold et al. 1996; see also Russell et al. 1996; Siegel et al. 1996; Weinstein et al. 1996). Included in these guidelines are recommendations to measure costs to the entire society rather than from the perspective of a given treatment-delivering organization; to include a “reference case” in research reports or an analysis conducted according to a common, standard set of economic assumptions to facilitate comparison with other studies; and to identify ethical problems that may arise in the course of analysis.