While knowledge of the implementation and outcome of programs is highly useful, in many cases it is critical to be informed about how program costs compare to their outcomes. A developing field of cost-benefit analysis provides a frame of reference for relating costs to benefits in either monetary terms or in terms of units of impact or outcome. While social programs may be more difficult to assess in cost-benefit terms than engineering and technical interventions, it is often possible to undertake analyses useful in determining the allocation of resources for intervention efforts and for influencing the policy and planning groups and political constituencies who determine the fate of social intervention efforts.
Cost-benefit and cost-effectiveness studies can be undertaken during the program planning phase. Such efforts have great utility, although the necessary empirical and experienced information necessary to undertake them appropriately may not be available. But while the conduct of these ex ante analyses is limited by practical considerations, it is usually feasible to undertake either cost-benefit or cost-effectiveness analyses as part of assessment of project outcome. These ex post analyses are important potential inputs into the subsequent planning and decision-making processes.