ABSTRACT
Evaluation among other things means the elaborations performed by technicians in order to help politicians in their decision-making activity. Examples of 'capture' of decision-makers by interest groups are outlined with special reference to European policies to create a single market for transport. Cost benefit analysis (CBA) is recommended to limit as far as possible 'discretionary' values directly given by the decision-makers. 'Welfare' implies its standard economic meaning: it is composed by: net social surplus, distribution effects, i.e. gains and losses of different social groups. CBA represents that the key objective of government is to maximise net social welfare, and provides measurements and guidelines for this maximisation. Estimating switch values that is the value of a given variable that may turn a profitable project into a less profitable one, is commonly used to carry out sensitivity analysis in CBA assessments.
