Identifying Policy Options to Achieve the Set of Objectives
The set of possible policy options taken into consideration in the policy appraisal process should include those considered realistic by at least one of the actors, or assumed as such by the analyst (Roy and Bouyssou 1993), and that contribute to the achievement of objectives. The definition of policy options depends both on the problem itself and the actors involved, and strongly influences the subsequent methodological steps. The set of options can be comprehensive, if every option is exclusive of any other, or fragmented, if certain combinations of individual options have to be considered.
Since MCA can and should ideally be based on an iterative process, the initial set of options might be modified during the policy formulation process, but should always include a comparison with the option of remaining with the status quo.
Evaluating Policy Options
In the MCA literature (Vincke 1992; Roy 1996; Belton and Stewart 2002), three main categories of approach are highlighted. However, it is recognized that these categories do not have sharp boundaries and that combinations of two such approaches can be envisaged (Roy 1996). The categories are: (1) multi-attribute utility (MAUT) methods, seeking to aggregate all points of view into a unique function which is to be optimized; (2) outranking methods, which construct and exploit a synthesizing relation based on the decision maker's preferences; and (3) interactive!trial-error methods, which explore the space of feasible options through a dialogue with the decision maker(s). Some guidelines exist on choosing a specific MCA approach (for example, Guitouni and Martel 1998), as well as recommendations on the desired properties it should have (for example, Munda 2004). In the following, the main MCA methods are summarized. For more details on the underlying assumptions and the related theoretical aspects, the interested reader may consult the references provided in the text.