http://sticerd.lse.ac.uk/dps/case/cp/CASEpaper44.pdf

Economic evaluation has an important role in helping to make decisions about the use of scarce resources in an explicit and rational manner, yet economic evaluation is not well-developed in many areas of social welfare. The paper concludes that in many areas of social welfare, economists should probably be less ambitious in terms of what they set out to achieve in terms of economic evaluation, but more ambitious in terms of the types of programme they can usefully help to evaluate and in terms of the range of techniques they are prepared to use, and give credence to, as part of an economic evaluation.