Qualitative researchers aim to gather an in-depth understanding of human behavior and the reasons that govern such behavior. The qualitative method investigates the why and how of decision making, not just what, where, when. Hence, smaller but focused samples are more often needed than large samples.
Focus groups, in-depth interviews, content analysis, ethnography, evaluation and semiotics are among the many approaches that are used, but qualitative research in its most basic form involves the analysis of any unstructured data, including: open-ended survey responses, literature reviews, audio recordings, pictures and web pages.
The reason they use small groups rather then large is to get more concise data as a pose to a very broad range of questions they could ask a wider audience.
I have used Qualitative data before whilst interviewing people questions for my Radio Assignment, I asked them in depth questions about what type of music they listened to and why. I found this type of research to be very informative.
sources:
http://www.qsrinternational.com/what-is-qualitative-research.aspx
http://www.digital-mr.com/digital-solutions/qualitative-research-online
Teenage Wasteland 