Qualitative research is defined as "research that derives data from observation, interviews, or verbal interactions and focuses on the meanings and interpretations of the participants." (Holloway & Wheeler, 1995, quoted in Health Sciences Library, 2021)
Qualitative research looks at meaning, perspectives and motivations rather than cause and effect. It typically has a smaller sample sizes and uses focus groups, interviews, and/or observation. The data it collects are "words" while quantitative research collects "numbers".
Several methodologies have been developed for qualitative research, including grounded theory, phenomenology, action research, and ethnography. For more information on qualitative research, see Synthesis of Qualitative Research or Qualitative Research Methods Overview.
References
Health Sciences Library. (2021, November 9). Findng qualitative research articles. University of Washington. https://guides.lib.uw.edu/hsl/qualres/strategies
Qualitative evidence can be challenging to find as the research methodologies are not always well-indexed in bibliographic databases.
Once you have your research question, you can use frameworks like PICO or SPIDER (see below) to help you identify the terms to search. Primary/unfiltered qualitative research includes studies, while secondary/filtered qualitative research might include systematic reviews or meta-syntheses.
Try these strategies for searching the literature:
Use subject headings
Databases use controlled keywords (known as thesaurus or subject terms) to categorise their content. MEDLINE and PubMed, for example, use Medical Subject Headings (MeSH). The subject headings vary for each database according to their indexing system. The term "qualitative research" is indexed in MEDLINE/PubMed as "Qualitative Research", while in CINAHL, the subject heading "Qualitative Studies" is complemented by narrower terms, including "Phenomenological Research" and "Grounded Theory".
Use keywords
Combine topic keywords with keywords relating to qualitative measures, such as perceptions, attitudes, opinions, feelings, beliefs, and experiences, and keywords relating to research methodologies, such as qualitative, ethnography/ethnographic, phenomenology, grounded theory, lived experience/life experiences, narrative, observation, case study, focus group, and interviews.
Acknowledgement: some of the content in this box is taken from the guide, Finding Qualitative Research Articles, created by the University of Washington's Health Sciences Library.
SPIDER is an alternative system to PICO for defining a research question. For more information see
S= Sample
P,I = Phenomenon of Interest
D = Design
E = Evaluation
R = Research Type
EXAMPLE from Cooke et al above:
Critical Qualitative Research in Healthcare: Exploring Philosophies, Politics and Practices by 
A Practical Guide to Using Qualitative Research with Randomized Controlled Trials by 
Routledge Handbook of Qualitative Research in Sport and Exercise by 
The SAGE handbook of qualitative research by 
Sharing Qualitative Research: Showing Lived Experience and Community Narratives by 
Social Research in Health and Illness: Case-based Approaches by 
