In health system research, it is often necessary to obtain information rapidly and economically, even if that means that the information will lose a degree of precision. Rapid appraisal techniques can be used if existing data are not sufficient to identify a problem.
They can be used to obtain additional information in an easy, inexpensive, but inevitably less accurate way than the use of an orthodox survey.
Rapid appraisal techniques are especially useful in the pilot phase of research, in conjunction with participatory research, and when the accuracy of the data does not have to be very high.
Two simple but powerful versions of these techniques are infrequent use. These are;