Core Category

The concept of core category is most often associated with the grounded theory method developed by Barney Glaser and Anselm Strauss, but it has been used in relation to other qualitative methods such as phenomenology. The terminology varies, and a core category may sometimes be referred to or indexed as a core theme, core meaning, core variable, or central category. A core category is the main theme, storyline, or process that subsumes and integrates all lower level categories in a grounded theory, encapsulates the data efficiently at the most abstract level, and is the category with the strongest explanatory power.

Core categories are identified and developed through the process of coding textual data. Three iterative stages of coding are outlined in grounded theory procedures. First, open coding is the process during which the researcher develops and refines codes through the constant comparison of phenomena in line-by-line scrutiny of the data. Second, during axial coding, relationships between these codes are identified and links between them are articulated. As these two stages progress, core categories develop and theory appears to cohere around them. Memos and diagrams aid axial coding through helping to identify core categories and show where the gaps are in the developing theory. Third, selective coding is used to saturate weak categories and fill gaps through returning to the original material and/or coding new material gathered specifically for this purpose. A common mistake is to commit to a core category too early in an analysis—before the scheme has been tested and verified against enough data. The general advice is to develop and write up theory around one core category at a time because this should constitute a substantial enough task.

Core categories are always theoretical and abstract, and sometimes they represent basic social (or structural) processes (BSPs). Not all grounded theory studies will identify a BSP, but when they do it is usually the organizing principle of the theory. BSPs are important in accounting for change over time and understanding how phenomena evolve, and often they contain an “-ing.” So, examples of core categories from the published literature include “integrating novelty” (from a study examining the transformational experience of insight) and “holding” (from a study of the use of transitional objects in psychotherapy) but also “relational closeness” (from a study of adult mother–daughter relationships).

There is some debate as to whether categories, including the core category, of a grounded theory analysis should be considered to have “emerged” from, or been “discovered” in, the data or whether categories should be conceptualized as having been constructed by, and hence an interpretation of, the researcher. The language of the original works on grounded theory suggests the former; however, the trend in grounded theory research today is toward constructionist interpretations. This has been clearly explored and articulated in the work of Kathy Charmaz.