In health system research, it is often necessary to obtain information rapidly and economically, even if that means the information will lose precision. Rapid appraisal techniques can be used if data are insufficient 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 data accuracy does not have to be very high.
Two simple but powerful versions of these techniques are infrequent use. These are;