Qualitative Sample Size

Qualitative analyses typically require a smaller sample size than quantitative analyses.  Qualitative sample sizes should be large enough to obtain enough data to sufficiently describe the phenomenon of interest and address the research questions. The goal of qualitative researchers should be the attainment of saturation.  Saturation occurs when adding more participants to the study does not result in additional perspectives or information.  Glaser and Strauss (1967) recommend the concept of saturation for achieving an appropriate sample size in qualitative studies.  Other guidelines have also been recommended.  For an ethnography, Morse (1994) suggested approximately 30 – 50 participants.  For grounded theory, Morse (1994) suggested 30 – 50 interviews, while Creswell (1998) suggested only 20 – 30.  For phenomenological studies, Creswell (1998) recommends 5 – 25 and Morse (1994) suggests at least six.  These recommendations can help a researcher estimate how many participants they will need, but ultimately, the required number of participants should depend on when saturation is reached.

References

Creswell, J. W. (1998). Qualitative inquiry and research design: Choosing among five traditions. Thousand Oaks, CA: Sage Publications.

Glaser, B. G. & Strauss, A. L. (1967). The discovery of grounded theory: Strategies for qualitative research. Piscataway, New Jersey: Transaction.

Morse, J. M. (1994). Designing funded qualitative research. In Denizin, N. K. & Lincoln, Y. S., Handbook of qualitative research (2nd Ed). Thousand Oaks, CA: Sage.