ABSTRACT
The choice of type of evaluation to use is normally made on the basis of how difficult it is to obtain data that will allow benefits to be measured or valued.
When benefits are traded in the market a value is put on them automatically, since the buyer must consider that they are worth at least what she paid. Sometimes it is possible indirectly to assess the value people place on benefits from their behaviour. For instance, even when they do not pay directly for a service, they may be willing to take time off work and travel, so there is a ‘price’ on the service. But often it is really not feasible to put any sensible money value on the outputs of health interventions. It may however be possible to compare them in some standard unit, such as years of healthy life gained or improvement in activity of daily living scores. Sometimes it is difficult even to find proxies for output or outcomes, and all that can be compared is the volume of services, but this type of measure is difficult to interpret.
