"Qualitative research is concerned with nonstatistical methods of inquiry and analysis of social phenomena. It draws on an inductive process in which themes and categories emerge through analysis of data collected by such techniques as interviews, observations, videotapes, and case studies. Samples are usually small and are often purposively selected. Qualitative research uses detailed descriptions from the perspective of the research participants themselves as a means of examining specific issues and problems under study.
Qualitative research differs from quantitative research in that the latter is characterized by the use of large samples, standardized measures, a deductive approach, and highly structured interview instruments to collect data for hypothesis testing (Marlow, 1993). In contrast to qualitative research, in quantitative research easily quantifiable categories are typically generated before the study and statistical techniques are used to analyze the data collected. Both qualitative and quantitative research are designed to build knowledge; they can be used as complementary strategies."
(Ruth McRoy)
"Interviews are a useful means of obtaining information from individuals who have been directly involved with the topic or period one is researching. Such individuals are 'primary sources' who can provide data or perspectives which may not be available from other sources. Individual interviews are normally used to establish or support particular points in a paper; a series of structured interviews may also comprise an entire 'original research component' of a paper if they form a coherent body of new information on the research topic."
(University of Tampere, 22 January 2012)