Incluye bibliografía

Different procedures for evaluating foreign exchange have been suggested in the project appraisal manuals of UNIDO and Little and Mirrlees. While it is widely agreed that the manuals differ in their practical procedures, there has been disagreement as to whether they are equivalent in principle. Using a model due to Boadway, we show that the manuals differ in principle. The Little-Mirrlees procedure can be given an interpretation which correctly values traded and non-traded goods in project appraisal, while the UNIDO formula for the shadow exchange rate is not required when the balance of payments constraint is binding.