"Cost-benefit analysis is a term that refers both to:

* a formal discipline used to help appraise, or assess, the case for a project or proposal, which itself is a process known as project appraisal; and
* an informal approach to making decisions of any kind.

Under both definitions the process involves, whether explicitly or implicitly, weighing the total expected costs against the total expected benefits of one or more actions in order to choose the best or most profitable option. The formal process is often referred to as CBA, or Benefit-cost analysis in the United States.

Closely related, but slightly different, formal techniques include cost-effectiveness analysis and benefit effectiveness analysis."
http://en.wikipedia.org/wiki/Cost-benefit_analysis