“The criterion for judging when to stop sampling the different groups pertinent to a category is the category’s theoretical saturation. Saturation means that no additional data are being found whereby the sociologist can develop properties of the category” – P61
As I see the same thing over and over in a category, I know I’m reaching this saturation point. I can go out of my way to look for a group that will really stretch the differences.
Once it seems to be I’m not able to add anything – I can move on to another category and work on saturating those too.
A key thing to remember is that categories and their properties are being sought out in order to develop a theory – NOT in order to judge the validity of the theory. So I’m looking for causality as opposed to strength or power. If I want to be able to show which causes are the more important – I need to look more statistically at the data. Perhaps I would need to randomly take a relevant sample. That isn’t the aim here.
Barney G. Glaser & Anselm L. Strauss. 1967. The Discovery of Grounded Theory. London: Weidenfeld and Nicolson.