Qualitative sample extensiveness in health education research

The use of qualitative methods is increasing in the health education literature, and there is need for more information on these methods and their use. This investigation looks at qualitative sampling practices as reported in the 93 qualitative or mixed-method studies published in Health Education & Behavior from 1980 to 2000. It focuses particularly on the extensiveness of sampling in this research (i.e., the volume and diversity of information collected about the phenomenon of interest). Among these studies, individual interviews averaged 104 +/- 134 informants (range 2 to 720) and 92 +/- 39 minutes. Focused group interviews averaged 10 groups (range 1 to 40) and 90 +/- 25 minutes. Observational studies usually occurred in multiple sites and involved approximately 16 to 24 months of fieldwork. Document analysis extensiveness varied considerably on a variety of indicators. Future qualitative research would benefit from more complete consideration and fuller reporting of sample extensiveness.