According to Rosato (1998), the multi-criteria analysis has significantly influenced the public  choice process and it can be of support to the decision maker to identify the  best option among the various possible alternatives (ex-ante evaluation) and to  assess the project Impacts (ex-post evaluation). Multicriteria analysis  comes from a critical review of cost-benefit analysis.
It aggregates the performance  rating of alternatives on different criteria into an overall performance  rating. Alternatives are rated on preference on each criterion. Given that  criteria are properties for which to measure the portfolio's performance on a  goal best. The alternative assessment is closely linked to the goal.
Unlike traditional  problem optimization, the multicriteria analysis orientates choice by selection  of more criteria, better in conflict between them and usually not measurable.
MCDA requires a  preselection of the alternatives and criteria to be analyzed through  qualitative and quantitative assessments, considering criteria with different  measures and not just monetary ones.
The criteria can be  subdivided into subcriters or in Gender classes (clusters); they indicate costs  and benefits to Decision Maker.
The multi-criteria  phases are as follows:

CONCLUSION