In 1967, Glaser and Strauss outlined a scheme for grounded theorizing, which is a method in qualitative research guiding researchers in finding linkages between data and theory.(1;2) Theoretical sampling and constant comparison are the main principles.
â€˜Theoretical sampling is the process of data collection for generating theory whereby the analyst jointly collects, codes, and analyses his data and decides what data to collect next and where to find them, in order to develop his theory as it emerges. This process of data collection is controlled by the emerging theoryâ€¦.The basic question in theoretical sampling â€¦is: what groups or subgroups does one turn to next in data collection? And for what theoretical purposeâ€™?(1)
The constant comparison aims to develop and refine theoretical categories and their properties.(2) Four stages can be discovered. The first stage is the categorization of codes grouping the different incidents in the data. The next step in the constant comparative method involves the integration of categories and their properties. What interaction can be found between the categories and how are they related? Theoretical saturation is the third stage when no new properties of categories can be found and no new interaction occurred. The last stage is writing the theory explaining the observed phenomena and providing illustrative examples such as quotes.
After years of experience Strauss and Corbin developed three distinctive successiveÂ ways of coding: open, axial and selective coding.(3) â€˜During open coding the data are broken down into discrete parts, closely examined, compared for similarities and differences, and questions are asked about the phenomena as reflected in the data.(3) During axial coding a single category is studied to determine its specific relations with other categories. Â During selective coding a single category is considered to be the core category and all other categories are regarded as subsidiary to the core.(2)
An example of research using the grounded theory methodology can be found in The diagnostic role of gut feelings in general practice.(4)
(1) Glaser B, Strauss A. The Discovery of Grounded Theory. Chicago: Aldine; 1967.
(2) Seale C. Grounding theory. In: Seale C, editor. The Quality of Qualitative Research.London: SAGE Publications Ltd; 1999. p. 87-105.
(3) Strauss AL, Corbin J. Basics of Qualitative Research: Grounded Theory Procedures and Techniques. Newbury Park: SAGE; 1990.
(4) Stolper CF, Van Bokhoven MA, Houben PHH, Van Royen P, Van de Wiel M, Van der Weijden T, et al. The diagnostic role of gut feelings in general practice. A focus group study of the concept and its determinants. BMC Fam Pract 2009 Feb 18;10(17).